132 690 03 Rev. M KohlerEngines.com
Service Manual
2 Safety
3 Maintenance
5 Specifi cations
21 Tools and Aids
24 Troubleshooting
29 Air Cleaner/Intake
31 Fuel System
50 Governor System
51 Lubrication System
53 Electrical System
61 Starter System
65 Emission Compliant Systems
68 Disassembly/Inspection and Service
81 Reassembly
IMPORTANT: Read all safety precautions and instructions carefully before operating equipment. Refer to operating
instruction of equipment that this engine powers.
Ensure engine is stopped and level before performing any maintenance or service.
KT610-KT620, KT715-KT745
2
Safety
SAFETY PRECAUTIONS
WARNING: A hazard that could result in death, serious injury, or substantial property damage.
CAUTION: A hazard that could result in minor personal injury or property damage.
NOTE: is used to notify people of important installation, operation, or maintenance information.
WARNING
Explosive Fuel can cause
fi res and severe burns.
Do not fi ll fuel tank while
engine is hot or running.
Gasoline is extremely fl ammable
and its vapors can explode if
ignited. Store gasoline only in
approved containers, in well
ventilated, unoccupied buildings,
away from sparks or fl ames.
Spilled fuel could ignite if it comes
in contact with hot parts or sparks
from ignition. Never use gasoline
as a cleaning agent.
WARNING
Rotating Parts can cause
severe injury.
Stay away while engine
is in operation.
Keep hands, feet, hair, and
clothing away from all moving
parts to prevent injury. Never
operate engine with covers,
shrouds, or guards removed.
WARNING
Carbon Monoxide can
cause severe nausea,
fainting or death.
Avoid inhaling exhaust
fumes. Never run engine
indoors or in enclosed
spaces.
Engine exhaust gases contain
poisonous carbon monoxide.
Carbon monoxide is odorless,
colorless, and can cause death if
inhaled.
WARNING
Accidental Starts can
cause severe injury or
death.
Disconnect and ground
spark plug lead(s) before
servicing.
Before working on engine or
equipment, disable engine as
follows: 1) Disconnect spark plug
lead(s). 2) Disconnect negative (–)
battery cable from battery.
WARNING
Hot Parts can cause
severe burns.
Do not touch engine
while operating or just
after stopping.
Never operate engine with heat
shields or guards removed.
WARNING
Cleaning Solvents can
cause severe injury or
death.
Use only in well
ventilated areas away
from ignition sources.
Carburetor cleaners and solvents
are extremely fl ammable. Follow
cleaner manufacturer’s warnings
and instructions on its proper and
safe use. Never use gasoline as a
cleaning agent.
CAUTION
Electrical Shock can
cause injury.
Do not touch wires while
engine is running.
CAUTION
Damaging Crankshaft
and Flywheel can cause
personal injury.
Using improper procedures can
lead to broken fragments. Broken
fragments could be thrown from
engine. Always observe and use
precautions and procedures when
installing fl ywheel.
KohlerEngines.com 32 690 03 Rev. M
3
Maintenance
32 690 03 Rev. M KohlerEngines.com
MAINTENANCE INSTRUCTIONS
WARNING
Before working on engine or equipment, disable engine as
follows: 1) Disconnect spark plug lead(s). 2) Disconnect
negative (–) battery cable from battery.
Accidental Starts can cause severe injury or
death.
Disconnect and ground spark plug lead(s)
before servicing.
Normal maintenance, replacement or repair of emission control devices and systems may be performed by any repair
establishment or individual; however, warranty repairs must be performed by a Kohler authorized dealer.
MAINTENANCE SCHEDULE
Every 25 Hours¹
● Service/replace precleaner. Air Cleaner/Intake
● Replace LPAC element (if not equipped with precleaner). Air Cleaner/Intake
Every 50 Hours¹
● Replace LPAC element (if equipped with precleaner). Air Cleaner/Intake
● Replace high performance air cleaner element (if not equipped with precleaner). Air Cleaner/Intake
Every 75 Hours¹
● Replace high performance air cleaner element (if equipped with precleaner). Air Cleaner/Intake
● Replace PRO performance air cleaner element (if not equipped with precleaner). Air Cleaner/Intake
Every 100 Hours¹
● Replace PRO performance air cleaner element (if equipped with precleaner). Air Cleaner/Intake
● Change oil and fi lter. Lubrication System
● Remove cooling shrouds and clean cooling areas. Air Cleaner/Intake
Every 100 Hours
● Check that all fasteners are in place and components are properly secured. Reassembly
● Replace fuel fi lter.
Every 300 Hours
3
● Change oil and fi lter (KOHLER PRO 10W-50 oil and KOHLER PRO fi lter only). Lubrication System
Every 500 Hours²
● Have valve lash checked/adjusted. Reassembly
Every 500 Hours
● Replace spark plugs and set gap. Electrical System
¹ Perform these procedures more frequently under severe, dusty, dirty conditions.
² Have a Kohler authorized dealer perform this service.
3
Option only if using KOHLER
®
PRO oil and PRO fi lter.
REPAIRS/SERVICE PARTS
Kohler genuine service parts can be purchased from Kohler authorized dealers. To fi nd a local Kohler authorized
dealer visit KohlerEngines.com or call 1-800-544-2444 (U.S. and Canada).
4
Maintenance
KohlerEngines.com 32 690 03 Rev. M
OIL RECOMMENDATIONS
All-season KOHLER
®
PRO 10W-50 Synthetic Oil is the
ideal oil for KOHLER engines. It is specifi cally formulated
to extend the oil and oil fi lter change interval to 300
Hours when paired with a KOHLER PRO Extended Life
Oil Filter.
300-Hour oil and oil fi lter change intervals are exclusive
to and only authorized on KOHLER engines that utilize
both the KOHLER PRO 10W-50 Synthetic Oil and
KOHLER PRO Extended Life Oil Filter. Alternative
engine oils and oil fi lters may be used with KOHLER
engines but require 100-Hour oil and oil fi lter change
intervals for proper maintenance. Oil must be API
(American Petroleum Institute) service class SJ or
higher. Select viscosity based on air temperature at time
of operation as shown below.
°F -20 0 20 32 40 60
50 80 100
°C -30 -20 -10 0 10 20 30 40
5W-30
10W-30
SAE 30
KOHLER PRO 10W-50
FUEL RECOMMENDATIONS
WARNING
Explosive Fuel can cause fi res and severe
burns.
Do not fi ll fuel tank while engine is hot or
running.
Gasoline is extremely fl ammable and its vapors can
explode if ignited. Store gasoline only in approved
containers, in well ventilated, unoccupied buildings,
away from sparks or fl ames. Spilled fuel could ignite
if it comes in contact with hot parts or sparks from
ignition. Never use gasoline as a cleaning agent.
NOTE: E15, E20 and E85 are NOT approved and
should NOT be used; eff ects of old, stale or
contaminated fuel are not warrantable.
Fuel must meet these requirements:
● Clean, fresh, unleaded gasoline.
● Octane rating of 87 (R+M)/2 or higher.
● Research Octane Number (RON) 90 octane minimum.
● Gasoline up to 10% ethyl alcohol, 90% unleaded is
acceptable.
● Methyl Tertiary Butyl Ether (MTBE) and unleaded
gasoline blend (max 15% MTBE by volume) are
approved.
● Do not add oil to gasoline.
● Do not overfi ll fuel tank.
● Do not use gasoline older than 30 days.
STORAGE
If engine will be out of service for 2 months or more
follow procedure below.
1. Add Kohler PRO Series fuel treatment or equivalent
to fuel tank. Run engine 2-3 minutes to get stabilized
fuel into fuel system (failures due to untreated fuel
are not warrantable).
2. Change oil while engine is still warm from operation
(NOT required if using KOHLER PRO 10W-50
full-synthetic oil). Remove spark plug(s) and pour
about 1 oz. of engine oil into cylinder(s). Replace
spark plug(s) and crank engine slowly to distribute
oil.
3. Disconnect negative (–) battery cable.
4. Store engine in a clean, dry place.
5
Specifi cations
32 690 03 Rev. M KohlerEngines.com
Engine Dimensions with Low Profi le or High Performance Air Cleaner-Flywheel Side
F
E
G
H
I
M
A
B
D
C
J
K
L
A 423.0 mm (16.65 in.) B 136.7 mm (5.38 in.) C 89.6 mm (3.53 in.) D 50.1 mm (1.97 in.)
E
Oil Fill and Dipstick
(Yellow)
F
Fuel Line Connection
Point
G Mounting Hole "A" H 136.9 mm (5.39 in.)
I 141.5 mm (5.57 in.) J 89.7 mm (3.53 in.) K 307.9 mm (12.12 in.) L
7.2 mm (0.28) Center
of Gravity
M
45.5 mm (1.79 in.)
Center of Gravity
6
Specifi cations
KohlerEngines.com 32 690 03 Rev. M
Engine Dimensions with Low Profi le or High Performance Air Cleaner-Oil Filter Side
A
B
C
D
E
F
G
H
I
J
K
L
M
A
355.1 mm (13.98 in.)
Low Profi le Air
Cleaner Removal
B
329.1 mm (12.96 in.)
Top of Low Profi le
Air Cleaner
C
159.4 mm (6.28 in.)
Center of Gravity
D
Engine Mounting
Surface
E
80.3 mm (3.16 in.)
Oil Filter
F Mounting Hole "A" G
51.2 mm (2.02 in.)
Oil Filter
H
134.0 mm (5.28 in.)
Spark Plug Center
Line
I 340.9 mm (13.42 in.) J 380.7 mm (14.99 in.) K Optional Fixed Guard L
392.1 mm (15.44 in.)
High Performance
Air Cleaner
Removal
M
354.2 mm (13.94 in.)
Top of High
Performance Air
Cleaner
7
Specifi cations
32 690 03 Rev. M KohlerEngines.com
Engine Dimensions with Low Profi le or High Performance Air Cleaner-Engine Mounting Surface (PTO End)
A
B
B C
E
F
G
H
I
J
L
P
N
M
O
D
T
S
R
K
G
L
L
Q
U
A 334.3 mm (13.16 in.) B 72.8 mm (2.87 in.) C 94.3 mm (3.71 in.) D 48.1 mm (1.89 in.)
E
Evap Connection
Point
F
4 X 5/16-18
UNC-2B in.
16.5 mm (0.649 in.)
Deep No Studs
G 30° H
50.0 mm (1.97 in.)
Exhaust Port #2
I 268.3 mm (10.56 in.) J 104.0 mm (4.10 in.) K 242.1 mm (9.53 in.) L 89.8 mm (3.54 in.)
M
18.0 mm (0.71 in.)
Oil Filter Removal
N 116.8 mm (4.60 in.) O Mounting Hole "A" P Rotation Direction
Q
248.1 mm (9.77 in.)
Starter Stud
R
4 X 9.005 mm (0.355
in.) 37.0 mm (1.46
in.) Deep on a Ø
254.0 mm (10.0 in.)
B.C.
S
93.1 mm (3.66 in.)
Starter Stud
T
312.0 mm (12.28 in.)
Throttle and Choke
Cable Mounting
Surface
U
50.0 mm (1.97 in.)
Exhaust Port #1
8
Specifi cations
KohlerEngines.com 32 690 03 Rev. M
Engine Dimensions with Low Profi le or High Performance Air Cleaner-Starter Side
A
B
C
D
E
F
G
H
A
55.8 mm (2.20 in.)
Starter Stud
B 13.0 mm (0.51 in.) C Mounting Hole "A" D 40.8 mm (1.61 in.)
E
Engine Mounting
Surface
F
72.0 mm (2.83 in.)
Exhaust Port #2
G
92.0 mm (3.62 in.)
Exhaust Port #1
H
154.0 mm (6.06 in.)
Spark Plug Center
Line
9
Specifi cations
32 690 03 Rev. M KohlerEngines.com
Engine Dimensions with Low Profi le or High Performance Air Cleaner-Valve Cover Side
A
B
C
D
E
F
A 87.6 mm (3.45 in.) B
Engine Mounting
Surface
C 152.9 mm (6.02 in.) D 4.4 mm (0.17 in.)
E Mounting Hole "A" F 39.8 mm (1.57 in.)
10
Specifi cations
KohlerEngines.com 32 690 03 Rev. M
Engine Dimensions with PRO Performance Air Cleaner-Flywheel Side
F
E
G
H
I
K
A
B
D
C
J
L
M
A 424.7 mm (16.72 in.) B 136.7 mm (5.38 in.) C 89.6 mm (3.53 in.) D 50.1 mm (1.97 in.)
E
Oil Fill and Dipstick
(Yellow)
F
Fuel Line Connection
Point
G 136.9 mm (5.39 in.) H Mounting Hole "A"
I 141.5 mm (5.57 in.) J 89.7 mm (3.53 in.) K
9.7 mm (0.38 in.)
Center of Gravity
L 307.9 mm (12.12 in.)
M
47.0 mm (1.85 in.)
Center of Gravity
11
Specifi cations
32 690 03 Rev. M KohlerEngines.com
Engine Dimensions with PRO Performance Air Cleaner-Oil Filter Side
A
B
C
D
E
F
G
H
I
L
M
K
J
A
458.7 mm (18.06 in.)
Air Cleaner
Removal
B
398.7 mm (15.70 in.)
Top of Air Cleaner
C
265.2 mm (10.44 in.)
Evap Connection
Point
D
166.5 mm (6.56 in.)
Center of Gravity
E
Engine Mounting
Surface
F
80.3 mm (3.16 in.)
Oil Filter
G Mounting Hole "A" H
51.2 mm (2.02 in.)
Oil Filter
I
134.0 mm (5.28 in.)
Spark Plug Center
Line
J 340.9 mm (13.42 in.) K 380.7 mm (14.99 in.) L Optional Fixed Guard
M
272.0 mm (10.71 in.)
Evap Connection
Point
12
Specifi cations
KohlerEngines.com 32 690 03 Rev. M
Engine Dimensions with PRO Performance Air Cleaner-Engine Mounting Surface (PTO End)
A
B B
C
E
F
G
H
I
J
L
P
N
M
O
D
S
R
K
Q
E
N
A 334.3 mm (13.16 in.) B 72.8 mm (2.87 in.) C 94.3 mm (3.71 in.) D
4 X 5/16-18 UNC-2B
in. 16.5 mm (0.649
in.) Deep No Studs
E 30° F
50.0 mm (1.97 in.)
Exhaust Port #2
G 242.1 mm (9.53 in.) H 104.0 mm (4.10 in.)
I 89.8 mm (3.54 in.) J
18.0 mm (0.71 in.)
Oil Filter Removal
K 116.8 mm (4.60 in.) L Mounting Hole "A"
M
248.1 mm (9.77 in.)
Starter Stud
N 89.8 mm (3.54 in.) O Rotation Direction P
4 X 9.005 mm
(0.355 in.) 37 mm
(1.46 in.) Deep on
a Ø
254 mm (10.0 in.)
B.C.
Q
93.1 mm (3.66 in.)
Starter Stud
R
312.0 mm (12.28 in.)
Throttle and
Choke Cable
Mounting Surface
S
50.0 mm (1.97 in.)
Exhaust Port #1
13
Specifi cations
32 690 03 Rev. M KohlerEngines.com
Engine Dimensions with PRO Performance Air Cleaner-Starter Side
A
B
C
D
E
F
G
H
A
55.8 mm (2.20 in.)
Starter Stud
B 13.0 mm (0.51 in.) C Mounting Hole "A" D 40.8 mm (1.61 in.)
E
Engine Mounting
Surface
F
72.0 mm (2.83 in.)
Exhaust Port #2
G
92.0 mm (3.62 in.)
Exhaust Port #1
H
154.0 mm (6.06 in.)
Spark Plug Center
Line
14
Specifi cations
KohlerEngines.com 32 690 03 Rev. M
Engine Dimensions with PRO Performance Air Cleaner-Valve Cover Side
A
B
C
D
E
F
A 87.6 mm (3.45 in.) B
Engine Mounting
Surface
C 152.9 mm (6.02 in.) D 4.4 mm (0.17 in.)
E Mounting Hole "A" F 39.8 mm (1.57 in.)
15
Specifi cations
32 690 03 Rev. M KohlerEngines.com
GENERAL SPECIFICATIONS
3,6
KT610
KT620 KT715 KT725 KT730 KT735 KT740* KT745
Bore 83 mm (3.27 in.)
Stroke
61 mm
(2.4 in.)
67 mm (2.64 in.)
69 mm
(2.72 in.)
Displacement
660 cc
(40.3 cu. in.)
725 cc (44 cu. in.)
747 cc
(46 cu. in.)
Oil Capacity (refi ll) 1.9 l (2.0 qt.)
Maximum Angle of Operation (@ full oil level)
4
25°
*KT740 engines with PRO Performance Air Cleaner have 747 cc (46 cu. in.) Displacement.
TORQUE SPECIFICATIONS
3,5
KT610
KT620 KT715 KT725 KT730 KT735 KT740 KT745
Auto Choke
eChoke
™
Stepper Motor to Bracket Fastener
Air Cleaner Base to Mounting Studs
3.1 N·m (27.4 in. lb.)
6.2-7.3 N·m (55-65 in. lb.)
Smart-Choke
™
Air Vane Defl ector to Intake Manifold
Air Cleaner Base to Mounting Studs
Bracket Assembly Screw
1 N·m (9 in. lb.)
6.2-7.3 N·m (55-65 in. lb.)
5 N·m (45 in. lb.)
Baffl e and Sheet Metal into Aluminum
M5 Thread Forming Fasteners 8.5 N·m (75 in. lb.) into new hole
4.0 N·m (35 in. lb.) into used hole
M6 Thread Forming Fasteners 10.7 N·m (95 in. lb.) into new hole
7.3 N·m (65 in. lb.) into used hole
Blower Housing and Sheet Metal
M3 HI-LO Screw 2.3 N·m (20 in. lb.)
M4 HI-LO Screw 2.8 N·m (25 in. lb.)
M5 Fasteners 6.2 N·m (55 in. lb.) into new hole
4.0 N·m (35 in. lb.) into used hole
M6 Fasteners 10.7 N·m (95 in. lb.) into new hole
7.3 N·m (65 in. lb.) into used hole
ENGINE IDENTIFICATION NUMBERS
Kohler engine identifi cation numbers (model, specifi cation and serial) should be referenced for effi cient repair,
ordering correct parts, and engine replacement.
Model . . . . . . . . . . . . . . . . . . . . . KT715
7000 Series Engine
Numerical Designation
Specifi cation . . . . . . . . . . . . . . . KT715-0001
Serial . . . . . . . . . . . . . . . . . . . . . 5023500328
Year Manufactured Code Factory Code
Code Year
50 2020
51 2021
52 2022
3
Values are in Metric units. Values in parentheses are English equivalents.
4
Exceeding maximum angle of operation may cause engine damage from insuffi cient lubrication.
5
Lubricate threads with engine oil prior to assembly.
6
Any and all horsepower (hp) references by Kohler are Certifi ed Power Ratings and per SAE J1940 & J1995 hp
standards. Details on Certifi ed Power Ratings can be found at KohlerEngines.com.
16
Specifi cations
KohlerEngines.com 32 690 03 Rev. M
TORQUE SPECIFICATIONS
3,5
KT610
KT620 KT715 KT725 KT730 KT735 KT740 KT745
Carburetor
Mounting Nut 6.2-7.3 N·m (55-65 in. lb.)
Connecting Rod
Cap Fastener (torque in increments)
Black Coating
Gray Metallic Coating
11.3 N·m (100 in. lb.)
13.6 N·m (120 in. lb.)
Crankcase
Breather Assembly
Outer Cover Stud
Outer Cover Hex Nut
6.2 N·m (55 in. lb.) into new hole
4.0 N·m (35 in. lb.) into used hole
1.3 N·m (11.5 in. lb.)
Oil Drain Plug 13.6 N·m (10 ft. lb.)
Cylinder Head
Head Bolt Fastener (torque in 2 increments) fi rst to 22.6 N·m (200 in. lb.)
fi nally to 41.8 N·m (370 in. lb.)
Rocker Arm Stud 11.3 N·m (100 in. lb.)
Flywheel
Retaining Screw 74.5 N·m (55 ft. lb.)
Fuel Pump
Screw 2.8 N·m (25 in. lb.)
Governor
Lever Nut 6.8 N·m (60 in. lb.)
Ignition
Spark Plug 27 N·m (20 ft. lb.)
Module Fastener 4.0-6.2 N·m (35-55 in. lb.)
Rectifi er-Regulator Fastener 4.0 N·m (35 in. lb.)
Intake Manifold
Mounting Fastener (torque in 2 increments) fi rst to 7.4 N·m (66 in. lb.)
fi nally to 9.9 N·m (88 in. lb.)
Muffl er
M8 Hex Nuts 24.4 N·m (216 in. lb.)
M8 Lock Nuts 27.8 N·m (246 in. lb.)
5/16-18 Capscrew 16.9 N·m (150 in. lb.)
Bracket Screw 9.9 N·m (88 in. lb.)
Oil Pan
Fastener 24.4 N·m (216 in. lb.)
Oil Pump
Screw (no torque sequence) 9.9 N·m (88 in. lb.)
Oil Sentry
™
Pressure Switch 4.5 N·m (40 in. lb.)
3
Values are in Metric units. Values in parentheses are English equivalents.
5
Lubricate threads with engine oil prior to assembly.
17
Specifi cations
32 690 03 Rev. M KohlerEngines.com
TORQUE SPECIFICATIONS
3,5
KT610
KT620 KT715 KT725 KT730 KT735 KT740 KT745
Solenoid (Starter)
Mounting Hardware 4.0-6.0 N·m (35-53 in. lb.)
Nut, Positive (+) Brush Lead 8.0-11.0 N·m (71-97 in. lb.)
Speed Control Bracket
Fastener 10.7 N·m (95 in. lb.) into new holes
7.3 N·m (65 in. lb.) into used holes
Starter Assembly
Thru Bolt
Inertia Drive
Solenoid Shift
4.5-5.7 N·m (40-50 in. lb.)
5.6-9.0 N·m (49-79 in. lb.)
Mounting Screw 23.8 N·m (211 in. lb.)
Brush Holder Mounting Screw 2.5-3.3 N·m (22-29 in. lb.)
Stator
Mounting Screw 8.8 N·m (78 in. lb.)
Valve Cover
Stamped Steel Cover Fastener 13.6 N·m (120 in. lb.)
Plastic Cover Fastener
Hex Flange
Pan Head
9.0 N·m (80 in. lb.)
6.2 N·m (55 in. lb.)
CLEARANCE SPECIFICATIONS
3
KT610
KT620 KT715 KT725 KT730 KT735 KT740 KT745
Camshaft
End Play 0.06/0.40 mm (0.0024/0.0157 in.)
Running Clearance 0.040/0.077 mm (0.0016/0.0030 in.)
Bore I.D.
New
Max. Wear Limit
20.000/20.025 mm (0.7874/0.7884 in.)
20.038 mm (0.7889 in.)
Bearing Surface O.D.
New
Max. Wear Limit
19.948/19.960 mm (0.7854/0.7858 in.)
19.945 mm (0.7852 in.)
Connecting Rod
Connecting Rod-to-Crankpin Running Clearance
New
Max. Wear Limit
0.037/0.083 mm (0.0015/0.0033 in.)
0.098 mm (0.0039 in.)
Connecting Rod-to-Crankpin Side Clearance 0.261/0.67 mm (0.0102/0.0264 in.)
Connecting Rod-to-Piston Pin Running Clearance 0.013/0.032 mm (0.0005/0.0013 in.)
Piston Pin End I.D.
New
Max. Wear Limit
17.013/17.027 mm (0.6698/0.6704 in.)
17.040 mm (0.6709 in.)
Crankcase
Governor Cross Shaft Bore I.D.
New
Max. Wear Limit
8.025/8.075 mm (0.3159/0.3179 in.)
8.088 mm (0.3184 in.)
3
Values are in Metric units. Values in parentheses are English equivalents.
5
Lubricate threads with engine oil prior to assembly.
18
Specifi cations
KohlerEngines.com 32 690 03 Rev. M
CLEARANCE SPECIFICATIONS
3
KT610
KT620 KT715 KT725 KT730 KT735 KT740 KT745
Crankshaft
End Play (free) 0.075/0.595 mm (0.0030/0.023 in.)
Bore (in crankcase)
New
Max. Wear Limit
40.974/40.987 mm (1.6131/1.6137 in.)
41.000 mm (1.6142 in.)
Bore (in oil pan)
New 40.974/41.000 mm (1.6457/1.6142 in.)
Crankshaft Bore (in oil pan)-to-Crankshaft
Running Clearance
New 0.039/0.087 mm (0.0015/0.0034 in.)
Flywheel End Main Bearing Journal
O.D. - New
O.D. - Max. Wear Limit
Max. Taper
Max. Out-of-Round
40.913/40.935 mm (1.6107/1.6116 in.)
40.840 mm (1.608 in.)
0.022 mm (0.0009 in.)
0.025 mm (0.0010 in.)
Oil Pan End Main Bearing Journal
O.D. - New
O.D. - Max. Wear Limit
Max. Taper
Max. Out-of-Round
40.913/40.935 mm (1.6107/1.6116 in.)
40.840 mm (1.608 in.)
0.022 mm (0.0009 in.)
0.025 mm (0.0010 in.)
Connecting Rod Journal
O.D. - New
O.D. - Max. Wear Limit
Max. Taper
Max. Out-of-Round
35.950/35.974 mm (1.4154/1.4163 in.)
35.950 mm (1.4154 in.)
0.018 mm (0.0007 in.)
0.025 mm (0.0010 in.)
T.I.R.
PTO End, Crank in Engine
Entire Crank, in V-Blocks
0.279 mm (0.0110 in.)
0.200 mm (0.0079 in.)
Cylinder Bore
Bore I.D.
New
Max. Wear Limit
Max. Out-of-Round
Max. Taper
83.006/83.031 mm (3.2679/3.2689 in.)
83.069 mm (3.2704 in.)
0.120 mm (0.0047 in.)
0.050 mm (0.0020 in.)
Cylinder Head
Max. Out-of-Flatness 0.076 mm (0.003 in.)
Governor
7 mm Hex End Cross Shaft End Play 0.25/3.15 mm (0.010/0.124 in.)
Governor Cross Shaft-to-Crankcase Running
Clearance 0.025/0.126 mm (0.0009/0.0049 in.)
Cross Shaft O.D.
New
Max. Wear Limit
7.949/8.000 mm (0.3129/0.3149 in.)
7.936 mm (0.3124 in.)
Governor Gear Shaft-to-Governor Running
Clearance
0.050/0.210 mm (0.0020/0.0083 in.)
Gear Shaft O.D.
New
Max. Wear Limit
5.990/6.000 mm (0.2358/0.2362 in.)
5.977 mm (0.2353 in.)
3
Values are in Metric units. Values in parentheses are English equivalents.
19
Specifi cations
32 690 03 Rev. M KohlerEngines.com
3
Values are in Metric units. Values in parentheses are English equivalents.
7
Measure 6 mm (0.2362 in.) above bottom of piston skirt at right angles to piston pin.
CLEARANCE SPECIFICATIONS
3
KT610
KT620 KT715 KT725 KT730 KT735 KT740 KT745
Ignition
Spark Plug Gap 0.76 mm (0.030 in.)
Module Air Gap 0.203/0.305 mm (0.008/0.012 in.)
Piston, Piston Rings, and Piston Pin
Piston-to-Piston Pin Running Clearance 0.006/0.017 mm (0.0002/0.0007 in.)
Pin Bore I.D.
New
Max. Wear Limit
17.006/17.012 mm (0.6695/0.6698 in.)
17.025 mm (0.6703 in.)
Pin O.D.
New
Max. Wear Limit
16.995/17.000 mm (0.6691/0.6693 in.)
16.994 mm (0.6691 in.)
Top Compression Ring-to-Groove Side Clearance 0.030/0.070 mm (0.001/0.0026 in.)
Middle Compression Ring-to-Groove Side
Clearance
0.030/0.070 mm (0.001/0.0026 in.)
Oil Control Ring-to-Groove Side Clearance 0.060/0.190 mm (0.0022/0.0073 in.)
Top Compression Ring End Gap
New Bore
Used Bore (Max.)
Middle Compression Ring End Gap
New Bore
Used Bore (Max.)
0.189/0.277 mm (0.0074/0.0109 in.)
0.531 mm (0.0209 in.)
1.519/1.797 mm (0.0598/0.0708 in.)
2.051 mm (0.0808 in.)
Thrust Face O.D.
7
New
Max. Wear Limit
82.978 mm (3.2668 in.)
82.833 mm (3.2611 in.)
Piston Thrust Face-to-Cylinder Bore
7
Running
Clearance
New
0.019/0.062 mm (0.0007/0.0024 in.)
Valves and Valve Tappets
Clearance 0.101/0.152 mm (0.0040/0.0060 in.)
Valve Tappet to Crankcase Running Clearance 0.013/0.073 mm (0.0005/0.0029 in.)
Intake Valve Stem-to-Valve Guide Running
Clearance
0.040/0.0780 mm (0.0016/0.0031 in.)
Exhaust Valve Stem-to-Valve Guide Running
Clearance
0.052/0.090 mm (0.0020/0.0035 in.)
Intake Valve Guide I.D.
New
Max. Wear Limit
7.040/7.060 mm (0.2772/0.2780 in.)
7.140 mm (0.2811 in.)
Exhaust Valve Guide I.D.
New
Max. Wear Limit
7.040/7.060 mm (0.2772/0.2780 in.)
7.160 mm (0.2819 in.)
Valve Guide Reamer Size
Standard
0.25 mm O.S.
7.050 mm (0.2776 in.)
7.300 mm (0.2874 in.)
Intake Valve Minimum Lift 8.500 mm (0.3346 in.)
Exhaust Valve Minimum Lift 8.500 mm (0.3346 in.)
Nominal Valve Face Angle 45°
20
Specifi cations
KohlerEngines.com 32 690 03 Rev. M
GENERAL TORQUE VALUES
Metric Fastener Torque Recommendations for Standard Applications
Property Class
Noncritical
Fasteners
Into Aluminum
Size
4.8
5.8
8.8
10.9 12.9
Tightening Torque: N·m (in. lb.) ± 10%
M4 1.2 (11) 1.7 (15) 2.9 (26) 4.1 (36) 5.0 (44) 2.0 (18)
M5 2.5 (22) 3.2 (28) 5.8 (51) 8.1 (72) 9.7 (86) 4.0 (35)
M6 4.3 (38) 5.7 (50) 9.9 (88) 14.0 (124) 16.5 (146) 6.8 (60)
M8 10.5 (93) 13.6 (120) 24.4 (216) 33.9 (300) 40.7 (360) 17.0 (150)
Tightening Torque: N·m (ft. lb.) ± 10%
M10 21.7 (16) 27.1 (20) 47.5 (35) 66.4 (49) 81.4 (60) 33.9 (25)
M12 36.6 (27) 47.5 (35) 82.7 (61) 116.6 (86) 139.7 (103) 61.0 (45)
M14 58.3 (43) 76.4 (56) 131.5 (97) 184.4 (136) 219.7 (162) 94.9 (70)
Torque Conversions
N·m = in. lb. x 0.113 in. lb. = N·m x 8.85
N·m = ft. lb. x 1.356 ft. lb. = N·m x 0.737
English Fastener Torque Recommendations for Standard Applications
Bolts, Screws, Nuts and Fasteners Assembled Into Cast Iron or Steel
Grade 2 or 5 Fasteners
Into Aluminum
Size Grade 2 Grade 5 Grade 8
Tightening Torque: N·m (in. lb.) ± 20%
8-32 2.3 (20) 2.8 (25) — 2.3 (20)
10-24 3.6 (32) 4.5 (40) — 3.6 (32)
10-32 3.6 (32) 4.5 (40) — —
1/4-20 7.9 (70) 13.0 (115) 18.7 (165) 7.9 (70)
1/4-28 9.6 (85) 15.8 (140) 22.6 (200) —
5/16-18 17.0 (150) 28.3 (250) 39.6 (350) 17.0 (150)
5/16-24 18.7 (165) 30.5 (270) — —
3/8-16 29.4 (260) — — —
3/8-24 33.9 (300) — — —
Tightening Torque: N·m (ft. lb.) ± 20%
5/16-24 — — 40.7 (30) —
3/8-16 — 47.5 (35) 67.8 (50) —
3/8-24 — 54.2 (40) 81.4 (60) —
7/16-14 47.5 (35) 74.6 (55) 108.5 (80) —
7/16-20 61.0 (45) 101.7 (75) 142.5 (105) —
1/2-13 67.8 (50) 108.5 (80) 155.9 (115) —
1/2-20 94.9 (70) 142.4 (105) 223.7 (165) —
9/16-12 101.7 (75) 169.5 (125) 237.3 (175) —
9/16-18 135.6 (100) 223.7 (165) 311.9 (230) —
5/8-11 149.5 (110) 244.1 (180) 352.6 (260) —
5/8-18 189.8 (140) 311.9 (230) 447.5 (330) —
3/4-10 199.3 (147) 332.2 (245) 474.6 (350) —
3/4-16 271.2 (200) 440.7 (325) 637.3 (470) —
Tools and Aids
2132 690 03 Rev. M KohlerEngines.com
Certain quality tools are designed to help you perform specifi c disassembly, repair, and reassembly procedures. By
using these tools, you can properly service engines easier, faster, and safer! In addition, you’ll increase your service
capabilities and customer satisfaction by decreasing engine downtime.
Here is a list of tools and their source.
NOTE: Not all tools listed are required to service this engine.
SEPARATE TOOL SUPPLIERS
Kohler Tools
Contact your local Kohler source of
supply.
SE Tools
415 Howard St.
Lapeer, MI 48446
Phone 810-664-2981
Toll Free 800-664-2981
Fax 810-664-8181
Design Technology Inc.
768 Burr Oak Drive
Westmont, IL 60559
Phone 630-920-1300
Fax 630-920-0011
TOOLS
Description Source/Part No.
Alcohol Content Tester
For testing alcohol content (%) in reformulated/oxygenated fuels.
Kohler 25 455 11-S
Camshaft Endplay Plate
For checking camshaft endplay.
SE Tools KLR-82405
Camshaft Seal Protector (Aegis)
For protecting seal during camshaft installation.
SE Tools KLR-82417
Dual Gauge Cylinder Leakdown Tester
For checking combustion retention and if cylinder, piston, rings, or valves are worn.
Individual component available:
Adapter 12 mm x 14 mm (Required for leakdown test on XT-6 engines)
Kohler 25 761 46-S
Design Technology Inc.
DTI-731-03
Dealer Tool Kit
Complete kit of Kohler required tools.
Components of 25 761 39-S
Ignition System Tester
Dual Gauge Cylinder Leakdown Test Tool
Oil Pressure Test Kit
Digital Vacuum/Pressure Tester
Kohler 25 761 39-S
Kohler 25 455 01-S
Kohler 25 761 46-S
Kohler 25 761 06-S
Kohler 25 455 22-S
Digital Vacuum/Pressure Tester
For checking crankcase vacuum.
Individual component available:
Rubber Adapter Plug
Kohler 25 455 22-S
Design Technology Inc.
DTI-721-10
EFI Service Kit
For troubleshooting and setting up an EFI engine.
Components of 24 761 01-S
Fuel Pressure Tester
Noid Light
90° Adapter
Code Plug, Red Wire
Code Plug, Blue Wire
Code Plug, Yellow Wire
Can Bus Reset Tool, Green Wire
Shrader Valve Adapter Hose
Wire Probe Set (2 pieces regular wire with clip; 1 piece fused wire)
Hose Removal Tool, Dual Size/End (also sold as individual Kohler tool)
K-Line Adapter Jumper Lead Wiring Harness
Kohler 24 761 01-S
Design Technology Inc.
DTI-019
DTI-021
DTI-023
DTI-027
DTI-029
DTI-028
DTI-030
DTI-037
DTI-031
DTI-033
Kohler 25 176 23-S
KOHLER
®
Diagnostic System (KDS) Gen 2
For Laptop or Desktop PC.
Components of 25 761 50-S
Engine Communication Module
7 Pin to DB9 Cable
USB Module to PC Cable
7 Pin to 4 Pin Adapter
Kohler 25 761 50-S
Kohler 25 761 47-S
Kohler 25 761 48-S
Kohler 25 761 49-S
Kohler 25 761 53-S
Mobile KDS (Wireless) Module
For mobile Android or iOS EFI diagnostics.
Individual component available:
Wireless Diagnostic System Interface Cable
Kohler 25 761 45-S
Kohler 25 761 44-S
Tools and Aids
22 32 690 03 Rev. MKohlerEngines.com
TOOLS
Description Source/Part No.
Flywheel Puller
For properly removing fl ywheel from engine.
SE Tools KLR-82408
Flywheel Anchor Bolts, Washers, Nuts Tool
Used with Flywheel Puller for properly removing fl ywheel from 5400 Series engine.
Kohler 25 086 753-S
Hose Removal Tool, Dual Size/End (also available in EFI Service Kit)
Used to properly remove fuel hose from engine components.
Kohler 25 455 20-S
Ignition System Tester
For testing output on all systems, including CD.
Kohler 25 455 01-S
Inductive Tachometer (Digital)
For checking operating speed (RPM) of an engine.
Design Technology Inc.
DTI-110
Oil Pressure Test Kit
For testing/verifying oil pressure on pressure lubricated engines.
Kohler 25 761 06-S
Rectifi er-Regulator Tester (120 volt current)
Rectifi er-Regulator Tester (240 volt current)
For testing rectifi er-regulators.
Components of 25 761 20-S and 25 761 41-S
CS-PRO Regulator Test Harness
Special Regulator Test Harness with Diode
Kohler 25 761 20-S
Kohler 25 761 41-S
Design Technology Inc.
DTI-031R
DTI-033R
Spark Advance Module (SAM) Tester
For testing SAM (ASAM and DSAM) on engines with SMART-SPARK
™
.
Kohler 25 761 40-S
Starter Servicing Kit (All Starters)
For removing and reinstalling drive retaining rings and brushes.
Individual component available:
Starter Brush Holding Tool (Solenoid Shift)
SE Tools KLR-82411
SE Tools KLR-82416
Stepper Motor Controller Tool
For testing operation of stepper motor/Digital Linear Actuator (DLA).
Kohler 25 455 21-S
Jumper Lead Tool
For use with Stepper Motor Controller Tool to test rotary stepper motor.
Kohler 25 518 43-S
Triad/OHC Timing Tool Set
For holding cam gears and crankshaft in timed position while installing timing belt.
Kohler 28 761 01-S
Valve Guide Reamer (K and M Series)
For properly sizing valve guides after installation.
Design Technology Inc.
DTI-K828
Valve Guide Reamer O.S. (Command Series)
For reaming worn valve guides to accept replacement oversize valves. Can be used
in low-speed drill press or with handle below for hand reaming.
Kohler 25 455 12-S
Reamer Handle
For hand reaming using Kohler 25 455 12-S reamer.
Design Technology Inc.
DTI-K830
AIDS
Description Source/Part No.
Camshaft Lubricant (Valspar ZZ613) Kohler 25 357 14-S
Dielectric Grease Loctite
®
51360
Kohler Electric Starter Drive Lubricant (Inertia Drive) Kohler 52 357 01-S
P80 Emulsion Lubricant Kohler 25 357 80-S
RTV Silicone Sealant
Loctite
®
5900
®
Heavy Body in 4 oz. aerosol dispenser.
Only oxime-based, oil resistant RTV sealants, such as those listed, are approved
for use. Permatex
®
the Right Stuff
®
1 Minute Gasket™ or Loctite
®
Nos. 5900
®
or
5910
®
are recommended for best sealing characteristics.
Kohler 25 597 07-S
Loctite
®
5910
®
Loctite
®
Ultra Black 598™
Loctite
®
Ultra Blue 587™
Loctite
®
Ultra Copper 5920™
Permatex
®
the Right Stuff
®
1
Minute Gasket™
Spline Drive Lubricant Kohler 25 357 12-S
Tools and Aids
2332 690 03 Rev. M KohlerEngines.com
FLYWHEEL HOLDING TOOL ROCKER ARM/CRANKSHAFT TOOL
A fl ywheel holding tool can be made out of an old junk
fl ywheel ring gear and used in place of a strap wrench.
1. Using an abrasive cut-off wheel, cut out a six tooth
segment of ring gear as shown.
2. Grind off any burrs or sharp edges.
3. Invert segment and place it between ignition bosses
on crankcase so tool teeth engage fl ywheel ring
gear teeth. Bosses will lock tool and fl ywheel in
position for loosening, tightening, or removing with a
puller.
A spanner wrench to lift rocker arms or turn crankshaft
may be made out of an old junk connecting rod.
1. Find a used connecting rod from a 10 HP or larger
engine. Remove and discard rod cap.
2. Remove studs of a Posi-Lock rod or grind off
aligning steps of a Command rod, so joint surface is
fl at.
3. Find a 1 in. long capscrew with correct thread size to
match threads in connecting rod.
4. Use a fl at washer with correct I.D. to slip on
capscrew and approximately 1 in. O.D. Assemble
capscrew and washer to joint surface of rod.
Troubleshooting
24 32 690 03 Rev. MKohlerEngines.com
Engine Cranks But Will Not Start
● Battery connected backwards.
● Blown fuse.
● Carburetor solenoid malfunction.
● Choke not closing.
● Clogged fuel line or fuel fi lter.
● Diode in wiring harness failed in open circuit mode.
● DSAI or DSAM malfunction.
● Empty fuel tank.
● Faulty electronic control unit.
● Faulty ignition coil(s).
● Faulty spark plug(s).
● Fuel pump malfunction-vacuum hose clogged or
leaking.
● Fuel shut-off valve closed.
● Ignition module(s) faulty or improperly gapped.
● Insuffi cient voltage to electronic control unit.
● Interlock switch is engaged or faulty.
● Key switch or kill switch in OFF position.
● Low oil level.
● Quality of fuel (dirt, water, stale, mixture).
● SMART-SPARK
™
malfunction.
● Spark plug lead(s) disconnected.
Engine Starts But Does Not Keep Running
● Faulty carburetor.
● Faulty cylinder head gasket.
● Faulty or misadjusted choke or throttle controls.
● Fuel pump malfunction-vacuum hose clogged or
leaking.
● Intake system leak.
● Loose wires or connections that intermittently ground
ignition kill circuit.
● Quality of fuel (dirt, water, stale, mixture).
● Restricted fuel tank cap vent.
Engine Starts Hard
● Clogged fuel line or fuel fi lter.
● Engine overheated.
● Faulty ACR mechanism.
● Faulty or misadjusted choke or throttle controls.
● Faulty spark plug(s).
● Flywheel key sheared.
● Fuel pump malfunction-vacuum hose clogged or
leaking.
● Interlock switch is engaged or faulty.
● Loose wires or connections that intermittently ground
ignition kill circuit.
● Low compression.
● Quality of fuel (dirt, water, stale, mixture).
● Weak spark.
TROUBLESHOOTING GUIDE
When troubles occur, be sure to check simple causes which, at fi rst, may seem too obvious to be considered. For
example, a starting problem could be caused by an empty fuel tank.
Some general common causes of engine troubles are listed below and vary by engine specifi cation. Use these to
locate causing factors.
Engine Will Not Crank
● Battery is discharged.
● Faulty electric starter or solenoid.
● Faulty key switch or ignition switch.
● Interlock switch is engaged or faulty.
● Loose wires or connections that intermittently ground
ignition kill circuit.
● Pawls not engaging in drive cup.
● Seized internal engine components.
Engine Runs But Misses
● Carburetor adjusted incorrectly.
● Engine overheated.
● Faulty spark plug(s).
● Ignition module(s) faulty or improperly gapped.
● Incorrect crankshaft position sensor air gap.
● Interlock switch is engaged or faulty.
● Loose wires or connections that intermittently ground
ignition kill circuit.
● Quality of fuel (dirt, water, stale, mixture).
● Spark plug lead(s) disconnected.
● Spark plug lead boot loose on plug.
● Spark plug lead loose.
Engine Will Not Idle
● Engine overheated.
● Faulty spark plug(s).
● Idle fuel adjusting needle(s) improperly set.
● Idle speed adjusting screw improperly set.
● Inadequate fuel supply.
● Low compression.
● Quality of fuel (dirt, water, stale, mixture).
● Restricted fuel tank cap vent.
Engine Overheats
● Cooling fan broken.
● Excessive engine load.
● Fan belt failed/off .
● Faulty carburetor.
● High crankcase oil level.
● Lean fuel mixture.
● Low cooling system fl uid level.
● Low crankcase oil level.
● Radiator, and/or cooling system components clogged,
restricted, or leaking.
● Water pump belt failed/broken.
● Water pump malfunction.
Engine Knocks
● Excessive engine load.
● Hydraulic lifter malfunction.
● Incorrect oil viscosity/type.
● Internal wear or damage.
● Low crankcase oil level.
● Quality of fuel (dirt, water, stale, mixture).
2532 690 03 Rev. M KohlerEngines.com
Troubleshooting
Engine Loses Power
● Dirty air cleaner element.
● Engine overheated.
● Excessive engine load.
● Restricted exhaust.
● Faulty spark plug(s).
● High crankcase oil level.
● Incorrect governor setting.
● Low battery.
● Low compression.
● Low crankcase oil level.
● Quality of fuel (dirt, water, stale, mixture).
Engine Uses Excessive Amount of Oil
● Loose or improperly torqued fasteners.
● Blown head gasket/overheated.
● Breather reed broken.
● Clogged, broken, or inoperative crankcase breather.
● Crankcase overfi lled.
● Incorrect oil viscosity/type.
● Worn cylinder bore.
● Worn or broken piston rings.
● Worn valve stems/valve guides.
Oil Leaks from Oil Seals, Gaskets
● Breather reed broken.
● Clogged, broken, or inoperative crankcase breather.
● Loose or improperly torqued fasteners.
● Piston blow by, or leaky valves.
● Restricted exhaust.
EXTERNAL ENGINE INSPECTION
NOTE: It is good practice to drain oil at a location away
from workbench. Be sure to allow ample time for
complete drainage.
Before cleaning or disassembling engine, make a
thorough inspection of its external appearance and
condition. This inspection can give clues to what
might be found inside engines (and cause) when it is
disassembled.
● Check for buildup of dirt and debris on crankcase,
cooling fi ns, grass screen, and other external surfaces.
Dirt or debris on these areas can cause overheating.
● Check for obvious fuel and oil leaks, and damaged
components. Excessive oil leakage can indicate a
clogged or inoperative breather, worn or damaged
seals or gaskets, or loose fasteners.
● Check air cleaner cover and base for damage or
indications of improper fi t and seal.
● Check air cleaner element. Look for holes, tears,
cracked or damaged sealing surfaces, or other
damage that could allow unfi ltered air into engine. A
dirty or clogged element could indicate insuffi cient or
improper maintenance.
● Check carburetor throat for dirt. Dirt in throat is further
indication that air cleaner was not functioning properly.
● Check if oil level is within operating range on dipstick.
If it is above, sniff for gasoline odor.
● Check condition of oil. Drain oil into a container; it
should fl ow freely. Check for metal chips and other
foreign particles.
Sludge is a natural by-product of combustion; a small
accumulation is normal. Excessive sludge formation
could indicate over rich fuel settings, weak ignition,
overextended oil change interval or wrong weight or
type of oil was used.
CLEANING ENGINE
WARNING
Cleaning Solvents can cause severe injury or
death.
Use only in well ventilated areas away from
ignition sources.
Carburetor cleaners and solvents are extremely
fl ammable. Follow cleaner manufacturer’s warnings
and instructions on its proper and safe use. Never use
gasoline as a cleaning agent.
After inspecting external condition of engine, clean
engine thoroughly before disassembly. Clean individual
components as engine is disassembled. Only clean
parts can be accurately inspected and gauged for wear
or damage. There are many commercially available
cleaners that will quickly remove grease, oil, and grime
from engine parts. When such a cleaner is used, follow
manufacturer’s instructions and safety precautions
carefully.
Make sure all traces of cleaner are removed before
engine is reassembled and placed into operation. Even
small amounts of these cleaners can quickly break down
lubricating properties of engine oil.
Troubleshooting
26 32 690 03 Rev. MKohlerEngines.com
Condition Conclusion
Crankcase breather clogged or inoperative. NOTE: If breather is integral part of valve cover and
cannot be serviced separately, replace valve
cover and recheck pressure.
Disassemble breather, clean parts thoroughly, check
sealing surfaces for fl atness, reassemble, and recheck
pressure.
Seals and/or gaskets leaking. Loose or improperly torque
fasteners.
Replace all worn or damaged seals and gaskets. Make
sure all fasteners are tightened securely. Use appropriate
torque valves and sequences when necessary.
Piston blow by or leaky valves (confi rm by inspecting
components).
Recondition piston, rings, cylinder bore, valves and
valves guides.
Restricted exhaust. Check exhaust screen/spark arrestor (if equipped). Clean
or replace as needed. Repair or replace any other
damaged/restricted muffl er or exhaust system parts.
CRANKCASE VACUUM TEST
WARNING
Carbon Monoxide can cause severe nausea,
fainting or death.
Avoid inhaling exhaust fumes. Never run
engine indoors or in enclosed spaces.
Engine exhaust gases contain poisonous carbon
monoxide. Carbon monoxide is odorless, colorless,
and can cause death if inhaled.
To test crankcase vacuum with manometer:
1. Insert rubber stopper into oil fi ll hole. Be sure pinch
clamp is installed on hose and use tapered adapters
to connect hose between stopper and one
manometer tube. Leave other tube open to
atmosphere. Check that water level in manometer is
at 0 line. Make sure pinch clamp is closed.
2. Start engine and run no-load high speed.
3. Open clamp and note water level in tube.
Level in engine side should be a minimum of
10.2 cm (4 in.) above level in open side.
If level in engine side is less than specifi ed (low/no
vacuum), or level in engine side is lower than level in
open side (pressure), check for conditions in table
below.
4. Close pinch clamp before stopping engine.
To test crankcase vacuum with vacuum/pressure gauge
(inches of water gauge only):
1. Remove dipstick or oil fi ll plug/cap.
2. Install adapter into oil fi ll/dipstick tube opening,
upside down over end of a small diameter dipstick
tube, or directly into engine if a tube is not used.
Insert barbed gauge fi tting into hole in stopper.
3. Run engine and observe gauge reading.
Analog tester–needle movement to left of 0 is a
vacuum, and movement to right indicates a
pressure.
Digital tester–depress test button on top of tester.
Crankcase vacuum should be a minimum of 10.2 cm
(4 in.) of water. If reading is below specifi cation, or if
pressure is present, check table below for possible
causes and conclusions.
WARNING
Rotating Parts can cause severe injury.
Stay away while engine is in operation.
Keep hands, feet, hair, and clothing away from all
moving parts to prevent injury. Never operate engine
with covers, shrouds, or guards removed.
A partial vacuum should be present in crankcase when engine is operating. Pressure in crankcase (normally caused
by a clogged or improperly assembled breather) can cause oil to be forced out at oil seals, gaskets, or other available
spots.
Crankcase vacuum is best measured with either a water manometer or a vacuum gauge (inches of water gauge only).
Complete instructions are provided in kits.
2732 690 03 Rev. M KohlerEngines.com
Troubleshooting
COMPRESSION TEST
A compression test is best performed on a warm engine. Clean any dirt or debris away from base of spark
plug(s) before removing them. Be sure battery is fully charged, choke is off , and throttle is wide open during test.
Compression should be at least 160 psi and should not vary more than 15% between cylinders.
CYLINDER LEAKDOWN TEST
A cylinder leakdown test can be a valuable alternative to a compression test. By pressurizing combustion chamber
from an external air source you can determine if valves or rings are leaking, and how badly.
Cylinder leakdown tester is a relatively simple, inexpensive leakdown tester for small engines. This tester includes a
quick-connect for attaching adapter hose and a holding tool.
Dual Gauge Test Procedure
1. Run engine until oil temperature reaches and
maintains 150°F (66°C) or more for a minimum of 5
minutes. Ideally, engine should be run under normal
load conditions.
2. Remove spark plug(s) and air fi lter from engine.
3. Rotate crankshaft until piston (of cylinder being
tested) is at top dead center (TDC) of compression
stroke. Hold engine in this position while testing.
Holding tool from kit can be used if PTO end of
crankshaft is accessible. Lock holding tool onto
crankshaft. Install a 3/8 in. breaker bar into hole/slot
of holding tool, so it is perpendicular to both holding
tool and crankshaft PTO.
If fl ywheel end is more accessible, use a breaker bar
and socket on fl ywheel nut/screw to hold it in
position. An assistant may be needed to hold
breaker bar during testing. If engine is mounted in a
piece of equipment, it may be possible to hold it by
clamping or wedging a driven component. Just be
certain engine cannot rotate off TDC in either
direction.
4. Connect an air source (at least 100 PSI) to tool.
5. Turn regulator knob clockwise (increase direction).
Confi rm both gauges read approximately the same
air pressure from 0 to 80 PSI. Note any
discrepancies between gauges for leakage
calculation. Release pressure by turning regulator
knob completely counterclockwise before
proceeding.
6. Install adapter hose into spark plug hole of cylinder
being tested. Use 12 mm x 14 mm adapter if
required.
7. Firmly hold engine at TDC. Connect other end of
adapter hose to tool quick connect. Turn regulator
knob clockwise (increase direction) until left gauge
needle reads 20 PSI.
NOTE: When piston is at TDC, little to no holding force
should be required when air pressure is applied
to cylinder. If excess holding force is required,
this indicates piston is not at TDC. Readjust as
necessary before proceeding.
8. Slowly turn regulator knob clockwise until left hand
gauge maintains selected test pressure (see chart
below).
Left Gauge Regulated Pressure Selection
80 PSI
Recommended for engines over 200 cc
or those exhibiting high leakage at 35 PSI setting.
35 PSI
Recommended for single cylinder
walk-behind push mower applications.
9. Compare right gauge reading to Test Pressure Chart
on next page to identify percentage of leakage. Also
refer to Leakdown Test Results chart on next page
for colors, conditions, and action required.
10. For engines exhibiting leakage in yellow or red zone,
repeat test procedure. Operate engine under normal
load conditions prior to test. Confi rm piston is at TDC
during test.
NOTE: To prevent damage to gauge assembly, always
turn pressure regulator knob to zero
(counterclockwise) after each test.
Troubleshooting
28 32 690 03 Rev. MKohlerEngines.com
Test Pressure Chart for Dual Gauge Tool
Left Gauge Regulated Pressure
Selection Right Gauge Reading in PSI
80 PSI
Recommended for engines over 200
cc or those exhibiting high leakage at
35 PSI setting.
80 72 64 56 48 40 32 24 16 8 0
35 PSI
Recommended for single cylinder
walk-behind push mower
applications.
35 31.5 28 24.5 21 17.5 14 10.5 7 3.5 0
Percentage of leakage 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Green Zone Yellow Zone Red Zone
Leakdown Test Results
Test Result Condition Action
Gauge reading in low
(green) zone.
Piston rings and cylinder in
good condition.
No further action required.
Gauge reading in
moderate (yellow)
zone.
Air escaping from crankcase
breather and/or dipstick tube.
Some wear present causing leakage from
combustion chamber to crankcase. Repair not
required at this time if breather system is
functioning normally.
Air escaping from exhaust. Exhaust valve leakage present, possibly due to
carbon deposits. Repair not required. Carbon
cleaning could be performed to reduce leakage.
Air escaping from intake. Intake valve leakage present, possibly due to
carbon deposits. Repair not required. Carbon
cleaning could be performed to reduce leakage.
Gauge reading in
high (red) zone.
Confi rm consecutive leakdown
test has been performed AFTER
engine has been operated under
normal load conditions.
Air escaping from crankcase
breather and/or dipstick tube.
Excess wear present causing leakage from
combustion chamber to crankcase. Breather
system will not function normally and will fail
crankcase vacuum test if this condition is truly
present. Engine disassembly and analysis
required to determine root cause and
correction.
Air escaping from exhaust. Excess exhaust valve leakage present, possibly
due to carbon deposits and/or valve to seat
sealing issues. Carbon cleaning may reduce
leakage. Valve grind and/or component
replacement may be necessary. Excess oil
consumption and/or excess heat is a suspect
cause and must be resolved to prevent
reoccurrence.
Air escaping from intake. Excess intake valve leakage present, possibly
due to carbon deposits and/or valve to seat
sealing issues. Carbon cleaning may reduce
leakage. Valve grind and/or component
replacement may be necessary. Excess oil
consumption through intake valve and/or
excess heat is a suspect cause and must be
resolved to prevent reoccurrence. Inspect
breather system components and intake valve
stem sealing.
29
Air Cleaner/Intake
32 690 03 Rev. M KohlerEngines.com
NOTE: Operating engine with loose or damaged air
cleaner components could cause premature
wear and failure. Replace all bent or damaged
components.
NOTE: Paper element cannot be blown out with
compressed air.
Rotate air cleaner cover levers outward to unlock cover;
remove air cleaner cover.
or
Move bails on air cleaner cover up; remove latches from
cover; remove cover.
Precleaner (if equipped)
1. Remove precleaner from paper element.
2. Replace or wash precleaner in warm water with
detergent. Rinse and allow to air dry.
3. Lightly oil precleaner with new engine oil; squeeze
out excess oil.
4. Reinstall precleaner over paper element.
Paper Element
1. Remove element from base; service precleaner.
Discard element.
2. Install precleaner over new paper element and install
on base.
Position air cleaner cover with levers outward over air
cleaner; turn levers inward to lock.
or
Reinstall cover; place latches onto cover; pull down bails
to secure cover.
AIR CLEANER
These systems are CARB/EPA certifi ed and components
should not be altered or modifi ed in any way.
Air Cleaner Components
C
C
B
B
H
D
E
E
F
F
B
J
E
K
K
F
A
G
I
A
Low-Profi le Air
Cleaner (LPAC)
B Air Cleaner Cover
C
Air Cleaner Cover
Lever
D LPAC Element
E Precleaner F Air Cleaner Base
G
High Performance
Air Cleaner
H
High Performance
Element
I
PRO Performance
Air Cleaner
J
PRO Performance
Element
K Bail
30
Air Cleaner/Intake
KohlerEngines.com 32 690 03 Rev. M
Air Cleaner Base
A
B
F
C
D
E
A
G
D
H
A Air Cleaner Base B Breather Hose
C Ground Lead D Solenoid Lead
E
Smart-Choke
™
Bracket Assembly
F Thermostat
G
eChoke
™
Bracket
Assembly
H Stepper Motor
Disassembly/Reassembly
NOTE: On engines equipped with eChoke
™
, stepper
motor has a special retract routine that can be
activated to ensure motor is in correct position
prior to removal or upon replacement of stepper
motor when a problem is shown to exist with
stepper motor assembly and carburetor.
Activation of this routine will occur by initiating
three (3) consecutive Key On–Off cycles. Every
Key On and Off should be > 2 seconds and <
3.5 seconds. Note that if no other connections
are disturbed, stepper motor will be repositioned
at next key ON and master module will go back
to normal choke operation mode.
If air cleaner base requires removal, proceed as follows:
1. Remove mounting screws for fuel pump (if
equipped), and blower housing.
2. Raise or remove blower housing for access to air
cleaner base.
3. Remove air cleaner components from base.
4. Remove nuts securing air cleaner base onto
mounting studs.
5. Disconnect ground lead and fuel shut-off solenoid
lead (if equipped).
6. If equipped with eChoke
™
, disconnect connecter
from stepper motor.
7. Remove Smart-Choke
™
or eChoke
™
bracket
assembly (if equipped).
8. Disconnect choke linkage from carburetor assembly.
9. Disconnect breather hose from air cleaner base,
then remove base and gasket.
10. Reverse procedure to reassemble components.
Torque nuts to 6.2-7.3 N·m (55-65 in. lb.). Torque
blower housing screws to 4.0 N·m (35 in. lb.), and
front HI-LO screws to 2.8 N·m (25 in. lb.). Torque
Smart-Choke
™
bracket assembly screw to 5 N·m (45
in. lb.).
BREATHER TUBE
Ensure both ends of breather tube are properly
connected.
AIR COOLING
WARNING
Hot Parts can cause severe burns.
Do not touch engine while operating or just
after stopping.
Never operate engine with heat shields or guards
removed.
Proper cooling is essential. To prevent over heating,
clean screens, cooling fi ns, and other external surfaces
of engine. Avoid spraying water at wiring harness or any
electrical components. Refer to Maintenance Schedule.
Fuel System
3132 690 03 Rev. M KohlerEngines.com
Typical carbureted fuel system and related components
include:
● Fuel tank.
● Fuel lines.
● In-line fuel fi lter.
● Fuel pump.
● Carburetor.
Fuel from tank is moved through in-line fi lter and fuel
lines by fuel pump. Fuel then enters carburetor fl oat bowl
and is drawn into carburetor body and mixed with air.
This fuel-air mixture is then burned in engine combustion
chamber.
FUEL RECOMMENDATIONS
Refer to Maintenance.
FUEL LINE
Low permeation fuel line must be installed on carbureted
Kohler Co. engines to maintain EPA and CARB
regulatory compliance.
FUEL PUMP
Some engines use a pulse style fuel pump. Pumping
action of pulse style pumps is created by oscillation of
positive and negative pressures within crankcase. This
pressure is transmitted to pulse pump through rubber
hose connected between pump and crankcase. Pumping
action causes diaphragm on inside of pump to pull fuel
in on its downward stroke and to push it into carburetor
on its upward stroke. Two check valves prevent fuel from
going backward through pump.
FUEL SYSTEM TESTS
When engine starts hard or turns over but will not start, fuel system might be causing problems. Test fuel system by
performing following test.
1. Check for fuel in combustion chamber.
a. Disconnect and ground spark plug leads.
b. Close choke on carburetor.
c. Crank engine several times.
d. Remove spark plug and check for fuel at tip.
2. Check for fuel fl ow from tank to fuel pump.
a. Remove fuel line from inlet fi tting of fuel pump.
b. Hold line below bottom of tank. Open shut-off
valve (if equipped) and observe fl ow.
Performance
Minimum fuel delivery rate must be 7.5 l/hr. (2 gal./hr.)
with a pressure at 0.3 psi and a fuel lift of 24 in. A
1.3 l/hr. (0.34 gal./hr.) fuel rate must be maintained at
5 Hz.
Fuel Pump Replacement
NOTE: Make sure orientation of new pump is consistent
with removed pump. Internal damage may occur
if installed incorrectly.
To replace pulse pump follow these steps. Note
orientation of pump before removing.
1. Disconnect fuel lines from inlet, outlet, and pulse
fi ttings on fuel pump.
2. Remove screws and take off pump.
3. Connect pulse line to new fuel pump and make sure
opposite end is properly connected into valve cover.
4. Attach new fuel pump using screws. Torque screws
to 2.8 N·m (25 in. lb.).
5. Reconnect fuel lines to inlet and outlet fi ttings and
secure with clamps.
AUTO CHOKE (if equipped)
If engine is equipped with Smart-Choke
™
or eChoke
™
,
identify design and follow appropriate troubleshooting
procedures starting on page 36 of this manual.
3. Check operation of fuel pump.
a. Remove fuel line from inlet fi tting of carburetor.
b. Crank engine several times and observe fl ow.
Condition Conclusion
Fuel at tip of spark plug. Fuel is reaching combustion chamber.
No fuel at tip of spark plug. Check fuel fl ow from fuel tank (step 2).
Fuel fl ows from fuel line. Check for faulty fuel pump (step 3).
If fuel pump is working, check for faulty carburetor. Refer
to Carburetor.
No fuel fl ow from fuel line. Check fuel tank cap vent, fuel pickup screen, in-line
fi lter, shut-off valve, and fuel line. Correct any observed
problem and reconnect line.
Fuel line condition. Check for a clogged fuel line. If fuel line is unobstructed,
check for overfi lled crankcase and/or oil in pulse line. If
checks don't reveal cause of problem, replace pump.
Fuel System
32 32 690 03 Rev. MKohlerEngines.com
CARBURETOR
WARNING
Explosive Fuel can cause fi res and severe
burns.
Do not fi ll fuel tank while engine is hot or
running.
Gasoline is extremely fl ammable and its vapors can
explode if ignited. Store gasoline only in approved
containers, in well ventilated, unoccupied buildings,
away from sparks or fl ames. Spilled fuel could ignite
if it comes in contact with hot parts or sparks from
ignition. Never use gasoline as a cleaning agent.
Keihin One-Barrel Carburetor Components
I
H
G
D
E
F
C
B
A
A Idle Speed Screw B Carburetor Body
C Idle Jet D Plug
E Main Jet F Float
G
Shut-off Solenoid
Assembly
H Fuel Bowl
I Choke Lever
Walbro One-Barrel Carburetor Components
G
F
E
C
D
B
A
A Idle Speed Screw B Carburetor Body
C Main Jet D Float
E Fuel Bowl F
Shut-off Solenoid
Assembly
G Choke Lever
Engines in this series are equipped with either a Keihin
or Walbro fi xed main jet carburetor. Most carburetors
utilize a fuel shut-off solenoid and feature a self-relieving
choke.
Troubleshooting Checklist
When engine starts hard, runs rough, or stalls at low
idle speed, check these areas before adjusting or
disassembling carburetor.
1. Make sure fuel tank is fi lled with clean, fresh
gasoline.
2. Make sure fuel tank cap vent is not blocked and is
operating properly.
3. Make sure fuel is reaching carburetor. This includes
checking fuel shut-off valve, fuel tank fi lter screen,
in-line fuel fi lter, fuel lines and fuel pump for
restrictions or faulty components as necessary.
4. Make sure air cleaner base and carburetor are
securely fastened to engine using gaskets in good
condition.
5. Make sure air cleaner element (including precleaner
if equipped) is clean and all air cleaner components
are fastened securely.
6. Make sure ignition system, governor system,
exhaust system, and throttle and choke controls are
operating properly.
Fuel System
3332 690 03 Rev. M KohlerEngines.com
Troubleshooting-Carburetor Related Causes
Condition Possible Cause Conclusion
Engine runs rich (indicated by black,
sooty exhaust smoke, misfi ring, loss
of speed and power, governor
hunting, or excessive throttle
opening).
Clogged air cleaner. Clean or replace air cleaner.
Choke partially closed during
operation.
Check choke lever/linkage to ensure
choke is operating properly.
Float level is set too high. Adjust fl oat (Keihin only, Walbro not
adjustable).
Dirt under fuel inlet needle. Remove needle; clean needle and
seat and blow with compressed air.
Bowl vent or air bleeds plugged. Clean vent, ports, and air bleeds.
Blow out all passages with
compressed air.
Leaky, cracked, or damaged fl oat. Submerge fl oat to check for leaks.
Engine runs lean (indicated by
misfi ring, loss of speed and power,
governor hunting, or excessive
throttle opening).
Float level is set too low. Adjust fl oat (Keihin only, Walbro not
adjustable).
Idle holes plugged; dirt in fuel delivery
channels.
Clean main fuel jet and all passages;
blow out with compressed air.
Fuel leaks from carburetor. Float level set too high. Adjust fl oat (Keihin only, Walbro not
adjustable).
Dirt under fuel inlet needle. Remove needle; clean needle and
seat and blow with compressed air.
Bowl vents plugged. Blow out with compressed air.
Carburetor bowl gasket leaks. Replace gasket.
FUEL SYSTEM
Fuel Shut-off Solenoid
Most carburetors are equipped with a fuel shut-off
solenoid. Solenoid is attached to fuel bowl. Solenoid has
a spring-loaded pin that retracts when 12 volts is applied
to lead, allowing fuel fl ow to main jet. When current is
removed, pin extends blocking fuel fl ow.
Below is a simple test, performed with engine off , that
can determine if solenoid is functioning properly:
1. Shut off fuel and remove solenoid from carburetor.
When solenoid is loosened and removed, gas will
leak out of carburetor. Have a container ready to
catch fuel.
2. Wipe tip of solenoid with a shop towel or blow with
compressed air to remove any remaining fuel. Take
solenoid to a location with good ventilation and no
fuel vapors present. You will also need a 12 volt
power source that can be switched on and off .
3. Be sure power source is switched OFF. Connect
positive power source lead to red lead of solenoid.
Connect negative power source lead to solenoid
body.
4. Turn power source ON and observe pin in center of
solenoid. Pin should retract with power ON and
return to its original position with power OFF. Test
several times to verify operation.
Carburetor Circuits
Float
Fuel level in bowl is maintained by fl oat and fuel inlet
needle. Buoyant force of fl oat stops fuel fl ow when
engine is at rest. When fuel is being consumed, fl oat will
drop and fuel pressure will push inlet needle away from
seat, allowing more fuel to enter bowl. When demand
ceases, buoyant force of fl oat will again overcome fuel
pressure, rising to predetermined setting and stop fl ow.
Slow and Mid-Range
At low speeds engine operates only on slow circuit. As
a metered amount of air is drawn through slow air bleed
jets, fuel is drawn through main jet and further metered
through slow jet. Air and fuel are mixed in body of slow
jet and exit to idle progression (transfer port) chamber.
From idle progression chamber, air fuel mixture is
metered through idle port passage. At low idle air/fuel
mixture is controlled by setting of idle fuel adjusting
screws. This mixture is then mixed with main body of
air and delivered to engine. As throttle plate opening
increases, greater amounts of air/fuel mixture are drawn
in through fi xed and metered idle progression holes.
As throttle plate opens further, vacuum signal becomes
great enough at venturi so main circuit begins to work.
Main (high-speed)
At high speeds/loads engine operates on main circuit.
As a metered amount of air is drawn through air jet,
fuel is drawn through main jet. Air and fuel are mixed
in main nozzles then enters main body of airfl ow where
further mixing of fuel and air occurs. This mixture is then
delivered to combustion chamber. Carburetor has a fi xed
main circuit; no adjustment is possible.
Fuel System
34 32 690 03 Rev. MKohlerEngines.com
Carburetor Adjustments
NOTE: Carburetor adjustments should be made only
after engine has warmed up.
Carburetor is designed to deliver correct fuel-to-air
mixture to engine under all operating conditions. Main
fuel jet is calibrated at factory and is not adjustable. Idle
fuel adjusting needles are also set at factory and are not
adjustable.
Idle Speed (RPM) Adjustment
1. Hold governor lever away from carburetor so throttle
lever is against idle speed (RPM) adjustment screw
of carburetor. Start engine and allow to warm up,
then adjust screw to set approximately 1450 RPM.
Check speed using a tachometer. Turn adjustment
screw (inner) clockwise (in) to increase or
counterclockwise (out) to decrease speed.
2. Release governor lever and check that throttle lever
is in idle position. Obtain equipment manufacturer’s
recommended idle speed (1750 RPM). All engines
have a bendable tab that is used to set this speed. A
pliers should be used to bend this tab to achieve
recommended speed. Governed idle speed (RPM) is
typically 300 RPM (approximate) higher than low idle
speed.
3. Move throttle lever to wide-open/full throttle position
and hold in this position. Turn high speed screw to
obtain intended high speed no-load RPM. Governed
idle speed must be set before making this
adjustment.
High Speed (RPM) Adjustment
1. With engine running, move throttle control to fast.
2. Turn inner adjustment screw outward to decrease, or
inward to increase RPM speed.
Carburetor Servicing
WARNING
Accidental Starts can cause severe injury or
death.
Disconnect and ground spark plug lead(s)
before servicing.
Before working on engine or equipment, disable
engine as follows: 1) Disconnect spark plug lead(s). 2)
Disconnect negative (–) battery cable from battery.
NOTE: Main and slow jets are fi xed and size specifi c
and can be removed if required. Fixed jets for
high altitudes are available.
● Inspect carburetor body for cracks, holes, and other
wear or damage.
● Inspect fl oat for cracks, holes, and missing or
damaged fl oat tabs. Check fl oat hinge and shaft for
wear or damage.
● Inspect fuel inlet needle and seat for wear or damage.
● Inspect spring loaded choke plate to make sure it
moves freely on shaft.
Float Setting (Keihin Only)
A
A 12 mm (0.472 in.)
NOTE: Inlet needle center pin is spring loaded. Make
sure fl oat assembly rests against fuel inlet
needle, without depressing center pin.
1. Perform removal procedures for appropriate air
cleaner and carburetor outlined in Disassembly.
2. Clean exterior surfaces of dirt or foreign material
before disassembling carburetor. Remove bowl
retaining screws, or solenoid assembly, and carefully
separate fuel bowl from carburetor. Do not damage
fuel bowl O-rings. Transfer any remaining fuel into
an approved container. Save all parts.
3. Remove fl oat pin (some carburetors may have a
screw which requires removal), and inlet needle.
Seat for inlet needle is not serviceable and should
not be removed.
4. Remove two screws securing top cover, gasket, and
ground lead (Keihin carburetors only). Discard
gasket and screws only.
5. Remove idle speed adjusting screw and spring from
carburetor. Discard parts.
6. Clean carburetor bowl and inlet seat areas as
required.
7. Carefully remove main jet from carburetor. After
main jet is removed, on some carburetors, main
nozzle can be removed through bottom of main
tower. Note orientation/direction of nozzle. Save
parts for cleaning and reuse.
8. Position of slow jet varies and is removable only on
some styles of carburetors. See correct illustration
for corresponding style of carburetor showing
location. Save parts for cleaning and reuse unless a
jet kit is also being installed. Clean slow jet using
compressed air. Do not use wire or carburetor
cleaner.
9. Carburetor is now disassembled for appropriate
cleaning and installation of parts in overhaul kit.
Further disassembly is not necessary. Throttle shaft
assembly, fuel inlet seat and idle fuel adjustment
screw are non-serviceable items and should not be
removed. Choke shaft assembly is serviceable,
however it should not be removed unless a choke
repair kit will be installed.
Fuel System
3532 690 03 Rev. M KohlerEngines.com
For Keihin Carburetors Only
To install choke repair kit go to step 10, otherwise go
to step 21.
10. Remove and discard plastic cap from top of choke
lever/shaft assembly.
11. Note position of spring legs and choke plate for
correct reassembly later.
12. Remove two screws attaching choke plate to choke
shaft. Pull shaft out of carburetor body and discard
removed parts.
13. Use a screw extractor (easy out) and remove
original choke shaft bushing with old choke lever
from carburetor housing. Save bushing to use as a
driver for installing new bushing. Discard old lever.
14. Clean I.D. of both choke shaft bores as required.
15. Insert new bushing through new choke lever from
outside, and start bushing in outer shaft bore.
Position choke lever so that protruding boss on
carburetor housing is between two stops formed in
choke lever.
16. Turn old bushing upside down and use it as a driver
to carefully press or tap new bushing into carburetor
body until it bottoms. Check that choke lever pivots
freely without restriction or binding.
17. Install new return spring onto new choke shaft, so
upper leg of spring is between two formed stops on
end of choke shaft.
18. Slide choke shaft and spring, into carburetor. Pivot
(preload) shaft and set inner leg of spring, against
formed stop within choke lever, as originally
assembled. Opposing leg of spring must still be
between formed stops of choke shaft.
19. Place a drop of Loctite® on threads of each new
screw. Install new choke plate to fl at side of choke
shaft and start two screws. Larger cutout must be on
right. Close choke and check plate alignment within
carburetor throat, then tighten screws securely. Do
not overtighten.
20. Check for proper operation and free movement of
parts. Install new cap.
21. Clean carburetor body, jets, vent ports, seats, etc.,
using a good commercially available carburetor
solvent. Use clean, dry compressed air to blow out
internal channels and ports. Inspect and thoroughly
check carburetor for cracks, wear, or damage.
Inspect fuel inlet needle seat for wear or damage.
Check spring loaded choke plate to make sure it
moves freely on shaft.
22. Clean carburetor fl oat bowl as required.
23. Install main nozzle and main jet into tower of
carburetor body.
24. Install slow jet and new plug into end of slow jet
tube.
25. Attach inlet needle to metal tang of fl oat with wire
clip. Formed 90° lip of metal tang should point up,
with needle valve hanging down.
26. Install new fl oat and new inlet needle down into seat
and carburetor body. Insert new pivot pin through
fl oat hinge and secure with new retaining screw.
27. Hold carburetor body so fl oat assembly hangs
vertically and rests lightly against fuel inlet needle.
Inlet needle should be fully seated but center pin of
needle (on retainer clip end) should not be
depressed. Check fl oat height adjustment.
28. Correct fl oat height adjustment is 12.0 mm
(0.472 in.) measured from fl oat bottom to body of
carburetor. Adjust fl oat height by carefully bending
metal tang of fl oat.
29. When proper fl oat height is obtained, carefully install
new O-ring for fuel bowl.
30. Install fuel bowl onto carburetor. Secure with four
original screws. Torque screws to 2.5 ± .3 N·m
(23 ± 2.6 in. lb.).
31. Install new cover gasket and top cover on
carburetor. Secure with two large-head screws and
attach ground lead (if equipped with a fuel solenoid),
to original screw location. Torque top cover screws
to 2.5 ± .3 N·m (23 ± 2.6 in. lb.).
32. Place new spring onto idle speed adjusting screw
and install into carburetor. Thread in until 3 or 4
threads are exposed, as an initial adjustment.
33. Reinstall carburetor using appropriate new
carburetor and air cleaner base gaskets.
34. Reconnect spark plug lead(s) and negative (–)
battery cable. Start engine and perform Idle Speed
(RPM) Adjustment.
For Walbro Carburetors Only
10. Clean carburetor body, jets, vent ports, seats, etc.,
using a good commercially available carburetor
solvent. Use clean, dry compressed air to blow out
internal channels and ports. Inspect and thoroughly
check carburetor for cracks, wear, or damage.
Inspect fuel inlet needle seat for wear or damage.
Check spring loaded choke plate to make sure it
moves freely on shaft.
11. Clean carburetor fl oat bowl as required.
12. Install main nozzle and main jet into tower of
carburetor body.
13. Install new solenoid gasket on solenoid.
Reassemble fuel bowl and solenoid.
14. Reinstall carburetor using appropriate new
carburetor and air cleaner base gaskets.
15. Reconnect spark plug lead(s) and negative (–)
battery cable. Start engine and perform Idle Speed
(RPM) Adjustment.
High Altitude Operation
If this engine is operated at an altitude of 4000 ft.
(1219 meters) or above, a high altitude carburetor
kit is required. To obtain high altitude carburetor kit
information or to fi nd a Kohler authorized dealer, visit
KohlerEngines.com or call 1-800-544-2444 (U.S. and
Canada).
This engine should be operated in its original
confi guration below 4000 ft. (1219 meters).
Operating this engine with the wrong engine
confi guration at a given altitude may increase its
emissions, decrease fuel effi ciency and performance,
and result in damage to the engine.
Fuel System
36 32 690 03 Rev. MKohlerEngines.com
Smart-Choke
™
An air vane defl ector assembly that operates by air from cooling fan opens choke partially when engine is running.
When engine is cold, a spring on air vane defl ector assembly, in conjunction with a bimetallic spring, holds choke
closed for starting. A bimetallic spring reacts to heat generated by electrical resistance as engine is running and opens
choke plate position. When engine is warm, bimetallic spring holds choke completely open, while engine is running.
Choke will be 2/3 closed when warm and not running. These two elements work together to operate a smooth choke
system that facilitates easy reliable starting.
As of this revision, there is an original design and an updated design. Identify design on engine being serviced and
follow those details to diagnose and troubleshoot.
Original Design Smart-Choke
™
Original design had a 3-terminal oil pressure switch as
part of system. Several other components in original
design have had improvements.
Thermostat
Thermostat Identifi cation
B
A
A Adjustable Thermostat
B Dual Position Thermostat
First thermostat was an adjustable thermostat that needs
to be reset if mounting screws are loosened or removed.
This was then replaced by a dual position thermostat
with mounting holes for CDI ignition position or MDI
ignition position.
Air Vane
Air Vane Identifi cation
B
A
A Early Design Air Vane
B Later Design Air Vane
Early design air vane was used with an adjustable
thermostat or a dual position thermostat mounted using
proper holes for ignition system on engine (plain holes
for CDI or M holes for MDI).
Later design air vane requires a dual position thermostat
ALWAYS mounted using plain holes.
Defl ector Support Tab (if equipped)
Some early production engines were built with a
defl ector support tab. This separate part was eliminated
and molded onto intake manifold.
Updated Design Smart-Choke
™
Updated design removed oil pressure switch from this
system and also replaced a 3-terminal oil pressure
switch with either a 1-terminal oil pressure switch (for
user notifi cation of low oil) or a plug. Wiring harness
also changed for proper connection to a 1-terminal oil
pressure switch and a 5 amp fuse was added in power
supply line to thermostat.
Fuel System
3732 690 03 Rev. M KohlerEngines.com
Smart-Choke
™
Components
A
B
C
D
E
F
I
J
K
L
M
O
N
Q
H
P
E
G
A Precleaner B Paper Element C Air Cleaner Base D Evap Hose
E
Smart-Choke
™
Bracket Assembly
F
Adjustable
Thermostat
G
Dual Position
Thermostat
H Solenoid Lead
I Air Cleaner Gasket J Control Assembly K Breather Hose L Stud
M Intake Manifold N
Choke Unloader
Linkage
O Ignition Module P
Defl ector Support Tab
(If Equipped)
Q Air Vane Defl ector
Troubleshooting Smart-Choke
™
Related Causes
Condition Possible Cause Conclusion
Engine starts hard, runs rough, or
stalls at idle speed.
Choke not closing. Check choke lever/linkage to ensure
choke is operating properly.
Check that bimetallic spring actuates
freely.
Engine runs rich (indicated by black,
sooty exhaust smoke, misfi ring, loss
of speed and power, governor
hunting, or excessive throttle
opening).
Choke partially closed during
operation.
Check choke lever/linkage to ensure
choke is operating properly.
Check that air vane is operating
freely.
Choke not opening. Check choke lever/linkage to ensure
choke is operating properly.
Check that air vane is operating
freely.
Check choke thermostat bracket
assembly.
Fuel System
38 32 690 03 Rev. MKohlerEngines.com
Smart-Choke
™
System Troubleshooting
Original Design Smart-Choke
™
System Oil
Pressure Switch
B
A
A Power In Terminal
B Power Out Terminal
These procedures are to be performed on a cold engine.
NOTE: Bimetallic spring assembly is pre-set at factory.
DO NOT attempt to adjust/change its settings.
NOTE: Do not remove or loosen thermostat screws.
Position is set at factory.
NOTE: Thermostat temperature must be at room
temperature before testing.
1. Remove air cleaner cover, and air cleaner from air
cleaner base.
2. Choke plate should be fully closed when engine is
cold.
3. There should be light spring tension holding choke
closed.
4. There should not be any binding when choke shaft
assembly is rotated, which could cause choke to
remain partially open.
5. Remove blower housing.
6. Check choke linkage and air vane defl ector
assembly for binding or debris build up. Gently
actuate linkage and observe that choke plate has full
range of movement (open and close).
7. Unplug red wire with black tracer power lead of
bimetallic spring assembly. Measure heat circuit
resistance of choke thermostat assembly, with a volt
ohm meter at room temperature (68°F/20°C).
8. Original Design Smart-Choke
™
System: Attach one
wire of meter to red wire w/yellow tracer terminal of
assembly, and other wire to ground of bracket or to
ground strip of assembly body.
Updated Design Smart-Choke
™
System: Attach one
wire of meter to red wire w/black tracer terminal of
assembly, and other wire to ground of bracket or to
ground strip of assembly body.
Thermostat resistance should read 15 ohms (+/- 10
ohms). If assembly is warm, allow unit to cool to
room temperature (68°F/20°C) for accurate testing.
If an infi nite (open) reading is found, replace
bimetallic spring choke bracket assembly. Air vane
linkage will not open choke plate fully when cold and
will not close choke plate fully when engine is warm.
9. Reinstall blower housing.
10. Start engine. Upon start up, choke plate should be
1/3 closed. Choke plate should gradually change to
full open position after 2 to 2-1/2 minutes of running.
This action is performed by bimetallic spring
assembly being heated. If choke plate fails to open,
recheck linkage for binding.
11. With engine running (Original Design Smart-Choke
™
System) or key switch ON (Updated Design Smart-
Choke
™
System), check voltage at bimetallic spring
choke bracket assembly. Using a DVOM, attach
black lead of meter to ground screw on assembly
bracket, and red lead of meter to red wire w/black
tracer.
12. Select DC VOLTS on your meter. You should see a
minimum of 12 volts DC.
If no voltage is present, test for voltage at oil
pressure switch (Original Design Smart-Choke
™
System).
If voltage is present at power in terminal but not at
power out terminal when engine is running, pressure
switch is potentially faulty. Remove switch and install
a pressure test gauge and start engine. Consult
troubleshooting section of this manual for oil
pressure testing instructions. If adequate pressure is
found, replace pressure switch and confi rm
operation/voltage readings.
13. If linkage is free and choke plate fails to open fully
after 2 minutes, check spring tension of bimetallic
assembly. If necessary, replace bimetallic spring
choke bracket assembly.
14. Reinstall air cleaner element and secure cover.
Thermostat
Diff erent styles of thermostats are used. Identify style
on engine and follow appropriate procedure to reset or
install.
Fuel System
3932 690 03 Rev. M KohlerEngines.com
Adjustable Thermostat Reset
NOTE: Do not remove or loosen thermostat screws. Position is set at factory.
NOTE: Thermostat temperature must be at room temperature before testing.
If thermostat is loosened or removed, use following procedure to reset position.
1. Unplug thermostat wire.
2. Thermostat position should be set to low position of adjustment range (E).
3. Once thermostat position is set, engine must be started at idle with thermostat wire disconnected to test system
function.
4. If engine runs correctly, no further adjustment is needed.
5. If engine speed does not increase to idle speed on start up, thermostat position must be adjusted by rotating
housing clockwise in 1 mm increments and retested. Position should not exceed high adjustment range shown
(D).
6. Plug in thermostat wire.
Adjustable Thermostat
B
D
E
F
D
E
F
C
A
A
Spring Tab Must be
Located in Lever Slot
B
Models KT725,
KT735
C
Models KT740,
KT745
D
High Position of
Adjustment
Range
E
Low Position of
Adjustment
Range
F
This Edge of Metallic
Ground Strap Must
Fall Within
Adjustment Range
G Lever Slot
G
Fuel System
40 32 690 03 Rev. MKohlerEngines.com
Dual Position Thermostat Installation
NOTE: Thermostat temperature must be at room temperature before testing.
1. Determine operating position of thermostat. Thermostat position is determined by ignition system: Capacitive
Discharge Ignition (CDI) or Magnetic Discharge Ignition (MDI).
For CDI systems secure thermostat in position (C).
For MDI systems secure thermostat in position (D).
2. Install Smart-Choke
™
bracket assembly with thermostat in proper position. Do not plug thermostat wire at this
time.
3. Engine must be started at idle with thermostat wire disconnected to test system function.
4. If engine runs correctly, no further adjustment is needed.
5. If engine speed does not increase to idle speed on start up, ensure spring tab (E) is engaged in lever slot (F) and
thermostat is in proper position for ignition system of engine.
6. Retest system function.
7. Plug in thermostat wire.
Dual Position Thermostat
D
C
D
C
E
B
A
A
CDI Ignition Module
(Top View)
B
MDI Ignition Module
(Top View)
C CDI Position D MDI Position
E
Spring Tab Must be
Located in Lever Slot
F Lever Slot
F
Fuel System
4132 690 03 Rev. M KohlerEngines.com
Starting an Engine Equipped with Smart-Choke
™
NOTE: Do not crank engine continuously for more than 10 seconds at a time. If engine does not start, allow a 60
second cool down period between starting attempts. Failure to follow these guidelines can burn out starter
motor.
NOTE: If engine develops suffi cient speed to disengage starter but does not keep running (a false start), engine
rotation must be allowed to come to a complete stop before attempting to restart engine. If starter is engaged
while fl ywheel is rotating, starter pinion and fl ywheel ring gear may clash, resulting in damage to starter.
1. Smart-Choke
™
system will automatically control choke plate position for starting.
2. Make sure equipment is in neutral.
3. Activate starter switch. Release switch as soon as engine starts.
If starter does not turn engine over, shut starter off immediately. Do not make further attempts to start engine until
condition is corrected. Do not jump start using another battery. See your Kohler authorized dealer for trouble
analysis.
4. For operation, after engine starts, move throttle and set desired engine operating speed.
Fuel System
42 32 690 03 Rev. MKohlerEngines.com
Electronic Choke (eChoke
™
)
eChoke
™
is an integrated control system that checks ambient and engine temperatures and monitors engine speed.
This system is integrated through wiring to a master ignition/control module. Extended cranking (beyond 10 seconds)
is not necessary, nor will it improve engine starting.
Calculations and unique software routines developed specifi cally for this Kohler engine operate a carburetor choke
lever through an assembly (bracket, linkage) to control a stepper motor. Power and ground are supplied to master
control and ignition module (Cylinder 2) which provides a signal for stepper motor by way of a control harness that is
routed through cylinder #2 baffl e. An interconnection harness between two modules may exist (model dependent).
eChoke Components (Includes ignition due to integrated system)
● Master & slave ignition modules (with interface cables)
● Stepper motor
● Stepper motor bracket, linkage, and associated fasteners
● Wire harness (for power and ground)
eChoke
™
Components
C
A
B
D
G
F
E
D
M
K
J
I
H
L
A Precleaner B Paper Element C
Stepper Motor
Bracket and
Hardware
D Stepper Motor
E Air Cleaner Base F Carburetor G Intake Manifold H
Ignition Module
Lead #2 Cylinder
I
Ignition Module
Lead #1 Cylinder
J
Master Ignition
Module
K
Slave Ignition
Module
L
Red/Green Stripe to
Constant Battery B+
Power
M
Master Controller
Stepper Motor
Harness/Connector
Fuel System
4332 690 03 Rev. M KohlerEngines.com
eChoke
™
System Standard Checks
NOTE: Procedures and troubleshooting may be easier
to perform with engine cover removed. Refer to
Disassembly/Inspection and Service and
Reassembly procedure.
Use these procedures and guides to troubleshoot this
system and its components. Perform a system reset
prior to troubleshooting to verify problem still exists. Start
with key switch in OFF position, operate through On-Off -
On sequence and restart engine.
There are standard checks that should be made initially
to help isolate possible problems:
1. Check choke assembly to ensure choke is properly
connected. (Link connected to carburetor and
stepper motor.)
2. Make sure link is located and connected properly.
3. Check for battery voltage (nonoperating), must be
greater than 12.2 VDC open circuit.
(Low battery voltage may prevent proper operation
of stepper motor.)
4. Check that constant power line (RED/GREEN stripe)
connection is connected directly to battery B+.
5. Check for continuity through constant power line
(possible fusible link failure).
6. Check for presence of constant (battery voltage) and
switched power at harness. (Blower housing must be
removed.)
7. Check that choke stepper motor is functioning.
(Remove air cleaner cover and element. Operate
key switch through On-Off -On sequence to inspect
for any choke movement.)
8. If blink codes indicate a temperature read failure or
RPM failure (see blink code info), then master
controller/ignition is at fault and needs to be
replaced.
9. If all standard checks are correct, proceed to Blink
Codes.
Blink Codes
NOTE: Use of any other type of lamp, other than LED,
could damage components.
eChoke
™
system is equipped with an MIL connector that
will allow connection of an LED lamp to show normal
eChoke
™
operation or specifi c error codes. This lead
(white/red stripe) with a bullet connector next to stepper
motor to which an LED (connected to lead and +12 volt
power line) can be connected to review operation or
look for error codes. Once a lamp is connected, operator
can attempt to run through a normal start/crank/run/
off sequence and monitor blink codes to determine if
controller operation is correct.
Both normal operation and error code indication is listed
in blink code table that follows. Note that code changes
for each level of operation.
Table shows both normal operation and failure mode
blinks codes. Normal operation blink codes will be
displayed when no failure modes are detected during
operation. These codes will only appear if there is no
captured failure blink code. Failure mode blink codes are
specifi c to integrated sensors associated with master
controller/ignition module.
Operational blink sequence only occurs when routine
associated to it is completed, until then LED will continue
blinking to previously completed routine.
eChoke Diagnostics and Failure Mode Subroutines
● DELAY=LED OFF 2 seconds
● ON=LED ON 0.5 second
● OFF=LED OFF 0.5 second
Fuel System
44 32 690 03 Rev. MKohlerEngines.com
Operational Tests
Test Step
Number
Operation
Description of
Operation
MIL Lamp Status
What is happening at
eChoke
™
1 Power Cycle
Remove and reconnect
engine connector.
ON
Choke system will cycle
to complete open and
then complete close.
1A Apply Power Turn key from OFF to ON.
ON OFF ON DELAY
System activated,
temperature read, waiting
for engine to crank &
start. Other MIL lamp
sequence indicates
failure mode 2B.
2A Crank to Start
Turn key from RUN to
CRANK.
ON OFF ON DELAY
Looking for starting
engine speed. IF engine
does not start, go to
Failure Mode description
1B or 3B based on MIL
lamp code.
3A Choke Adjusting
Engine started, release
Key to RUN position.
ON OFF ON OFF ON
DELAY
eChoke
™
moving to open
position.
4A Normal
Choke operation
completed.
ON
eChoke
™
stays in open
position.
5A Engine Shutdown
Turn Key from RUN to
OFF.
ON DELAY
Once engine has come
to a stop, choke will fully
close.
6A Power Saver Mode
System will switch to
power saver mode after 30
minutes without engine
speed reading.
OFF
System goes into power
saver mode after 30
minutes of non use due
to shut down by seat
switch activation or when
key switch moved to
OFF. If activated by
safety switch shutdown,
operator MUST move to
key OFF to reset
sequence.
Fuel System
4532 690 03 Rev. M KohlerEngines.com
Failure Modes
1B Failure to Start
ON
Pause at RUN and attempt to CRANK
engine.
Limit cranking time to about 5 seconds.
For fi rst 4 failed crank attempts, choke
will reposition at each attempt. After
four (4) attempts, key OFF and make
one fi nal attempt to start.
Check other components (spark plug,
ignition, carburetor, fuel solenoid).
2B Temperature Read Failure
ON OFF ON OFF ON OFF
ON OFF ON DELAY
Faulty temperature sensor. System will
keep choke closed at Key ON and
ramp to open within 10 seconds of
engine starting if this is root failure.
Replace Master controller/ignition.
3B RPM Read Failure
ON OFF ON OFF ON OFF
ON DELAY
System defaults to this failure after 30
seconds of being in Key ON and no
RPM.
Choke will open to half position.
Error clears if system reads RPM when
engine is cranking.
Replace Master controller/ignition.
Fuel System
46 32 690 03 Rev. MKohlerEngines.com
Troubleshooting eChoke
™
Related Causes
Condition Possible Cause Conclusion
Engine starts hard, runs rough, or
stalls at idle speed.
Choke not closing/moving
a. Incorrect set up of stepper
motor/link/bracket to
carburetor.
b. Broken or missing link.
Stepper motor/bracket/link assembly
must allow for full travel, make sure
link is located properly and
connected.
c. Loss of constant power or
switched power.
d. Loss of system ground.
e. Fusible link is open.
f. Stepper motor not functioning
or shaft has fallen out of
motor.
g. Electronic component in
Master ignition/control module
is not functioning.
Bad wire harness connection, fusible
link failure.
Component failure in Master
controller/ignition.
Bad Master Controller harness.
Engine runs rich (indicated by black,
sooty exhaust smoke, misfi ring, loss
of speed and power, governor
hunting, or excessive throttle
opening).
Choke partially closed during
operation.
a. Incorrect set up of stepper
motor/link/bracket to
carburetor.
b. Broken or missing link.
Stepper motor/bracket/link assembly
must allow for full travel, make sure
link is located properly and
connected.
c. Loss of constant power or
switched power.
d. Loss of system ground.
e. Fusible link is open.
f. Stepper motor not functioning
or shaft has fallen out of
motor.
g. Electronic component in
Master ignition/control module
is not functioning.
Bad wire harness connection, fusible
link failure.
Component failure in Master
controller/ignition.
Bad Master Controller harness.
Engine runs lean (indicated by
misfi ring, loss of speed and power,
governor hunting, or excessive
throttle opening).
Key integrated component in Master
ignition/control module is not
functioning.
Bad ignition module on specifi c
cylinder.
Incorrect set up of stepper motor/link/
bracket to carburetor.
Stepper motor/bracket/link assembly
must allow for full travel, make sure
link is located properly and
connected.
Fuel System
4732 690 03 Rev. M KohlerEngines.com
Starting an Engine Equipped with eChoke
™
1. This eChoke
™
system automatically controls choke
plate position for starting.
2. Make sure equipment is in neutral and brake is
engaged.
3. Activate starter switch. Release switch as soon as
engine starts.
4. For operation, after engine starts, move throttle and
set desired engine operating speed.
5. If engine does not start, remove air cleaner cover,
and air cleaner from air cleaner base.
6. Confi rm connection of stepper motor assembly to
carburetor.
7. With key switch set to OFF, choke plate should
nearly fully closed, stepper motor for eChoke should
be near full extension (expanded bellows).
8. With engine/ambient temperature above 40°F (4°C),
turn key switch from OFF to RUN. There should be a
noticeable movement of choke plate.
9. If no movement:
a. Shut off key switch and test for full travel of
actuator by disconnection and reconnection of
constant power (RED/GREEN STRIPE) at engine
connector.
b. If there is still no movement, separate tests to
validate battery voltage and power and ground
connection to master controller need to be
performed.
10. If movement is noted, attempt to crank and start
engine. (Do not exceed 10 seconds of cranking.)
11. If engine does not start:
Release key to RUN position, (do not shut OFF),
pause, movement of choke should be noted.
Repeat from beginning of step 10 (this routine can
be attempted 4 times). Choke should be fully
relieved after fi nal attempt. If eChoke
™
assembly
moves choke plate through each attempt, but engine
still did not start, problem is not associated with
eChoke
™
, but is rather another system or component
issue.
Fuel System
48 32 690 03 Rev. MKohlerEngines.com
Governor/Throttle Control Connections
M
C
E
I
H
I
H
A
F
J
K
B
B
E
D
C
F
A
E
G
C
A Left Side Pull B Cable Clamp C Speed Control Lever D Speed Setting Lever
E Choke Lever F Right Side Pull G Contact Point H Choke Control Cable
I Throttle Control Cable J
Dual Control High Speed
Lever Stop Screw (Do
Not Remove)
K
High Speed Adjusting
Screw
L Choke Linkage
M
High Speed Control
Lever
Fuel System
4932 690 03 Rev. M KohlerEngines.com
Starting an Engine Equipped with Unitized Throttle
and Choke Control
NOTE: Do not crank engine continuously for more than
10 seconds at a time. If engine does not start,
allow a 60 second cool down period between
starting attempts. Failure to follow these
guidelines can burn out starter motor.
NOTE: If engine develops suffi cient speed to disengage
starter but does not keep running (a false start),
engine rotation must be allowed to come to a
complete stop before attempting to restart
engine. If starter is engaged while fl ywheel is
rotating, starter pinion and fl ywheel ring gear
may clash, resulting in damage to starter.
1. For a Cold or Warm Engine – Place throttle/choke
control into fast/choke ON position. This will also
place choke into ON position.
2. Make sure equipment is in neutral.
3. Activate starter switch. Release switch as soon as
engine starts.
If starter does not turn engine over, shut starter off
immediately. Do not make further attempts to start
engine until condition is corrected. Do not jump start
using another battery. See your Kohler authorized dealer
for trouble analysis.
4. For Operation – After engine starts, move throttle/
choke control from fast/choke ON position and set
desired engine operating speed (between slow and
fast position).
UNITIZED THROTTLE AND CHOKE CONTROL
Some engines are equipped with a unitized throttle and
choke control. This assembly controls choke and engine
speed with a single lever. Engines with a unitized throttle
and choke control will have either a left side pull or a
right side pull.
Throttle Cable Adjustment
NOTE: Choke is placed ON by moving throttle control
slightly past fast position. If throttle control does
not have a designated choke ON position, be
sure to leave suffi cient throttle control travel past
fast position. This will enable choke to be placed
ON.
1. Loosen control cable clamp.
2. Place throttle control lever of equipment into fast or
high speed position.
3. Pull on outer shield of throttle control cable until
speed control lever rotates and makes contact with
choke lever. Tighten cable clamp securely.
Governor System
50 32 690 03 Rev. MKohlerEngines.com
GOVERNOR
Governed speed setting is determined by position of throttle control. It can be variable or constant, depending on
engine application.
Governor is designed to hold engine speed constant under changing load conditions. Most engines are equipped with
a centrifugal fl yweight mechanical governor. Governor gear/fl yweight mechanism of mechanical governor is mounted
inside oil pan and is driven off gear on camshaft.
Governor Components
F
E
B
A
D
J
L
K
I
M
Inside Engine
C
D
G
H
A Throttle Lever B Throttle Linkage C Nut D Governor Lever
E Governor Spring F Choke Linkage G
Round Cross Shaft
End
H
7 mm Hex Cross
Shaft End
I Flyweight J Regulating Pin K Governor Gear L
Locking Tab
Thrust Washer
M Shaft
This governor design works as follows:
● Centrifugal force acting on rotating governor gear
assembly causes fl yweights to move outward as
speed increases. Governor spring tension moves
them inward as speed decreases.
● As fl yweights move outward, they cause regulating pin
to move outward.
● Regulating pin contacts tab on cross shaft causing
shaft to rotate.
● One end of cross shaft protrudes through crankcase.
Rotating action of cross shaft is transmitted to throttle
lever of carburetor through external throttle linkage.
● When engine is at rest, and throttle is in fast position,
tension of governor spring holds throttle plate open.
When engine is operating, governor gear assembly is
rotating. Force applied by regulating pin against cross
shaft tends to close throttle plate. Governor spring
tension and force applied by regulating pin balance
each other during operation, to maintain engine
speed.
● When load is applied and engine speed and governor
gear speed decreases, governor spring tension moves
governor arm to open throttle plate wider. This allows
more fuel into engine, increasing engine speed. As
speed reaches governed setting, governor spring
tension and force applied by regulating pin will again
off set each other to hold a steady engine speed.
Governor Adjustments
NOTE: Do not tamper with governor setting. Overspeed
is hazardous and could cause personal injury.
Initial Adjustment Procedure
Make this adjustment whenever governor arm is
loosened or removed from cross shaft. To ensure proper
adjustment, make sure throttle linkage is connected
to both governor arm and throttle lever on carburetor.
Adjust as follows:
1. Make sure throttle linkage is connected to governor
arm and throttle lever on carburetor.
2. Loosen nut holding governor lever to cross shaft.
3. Move governor lever toward carburetor as far as it
will go (wide open throttle) and hold in this position.
4. Round Cross Shaft End: Insert a long thin rod or
tool into hole on cross shaft and rotate shaft
counterclockwise (viewed from end) as far as it will
turn, then torque nut to 6.8 N·m (60 in. lb.).
7 mm Hex Cross Shaft End: Use 7 mm hex socket
on end of cross shaft and rotate shaft
counterclockwise (viewed from end) as far as it will
turn, then torque nut to 6.8 N·m (60 in. lb.).
51
Lubrication System
32 690 03 Rev. M KohlerEngines.com
OIL RECOMMENDATIONS
Refer to Maintenance.
CHECK OIL LEVEL
NOTE: To prevent extensive engine wear or damage,
never run engine with oil level below or above
operating range indicator on dipstick.
Ensure engine is cool. Clean oil fi ll/dipstick areas of any
debris.
1. Remove dipstick; wipe oil off .
2. Reinsert dipstick into tube; press completely down.
3. Remove dipstick; check oil level. Level should be at
top of indicator on dipstick.
4. If oil is low on indicator, add oil up to top of indicator
mark.
5. Reinstall and secure dipstick.
CHANGE OIL AND FILTER
Change oil while engine is warm.
1. Clean area around oil fi ll/dipstick. Remove drain plug
and oil fi ll/dipstick. Allow oil to drain completely.
2. Clean area around oil fi lter. Place a container under
fi lter to catch any oil and remove fi lter. Wipe off
mounting surface. Reinstall drain plug. Torque to
13.6 N·m (10 ft. lb.).
3. Place new fi lter in shallow pan with open end up. Fill
with new oil until oil reaches bottom of threads. Allow
2 minutes for oil to be absorbed by fi lter material.
4. Apply a thin fi lm of clean oil to rubber gasket on new
fi lter.
5. Refer to instructions on oil fi lter for proper
installation.
6. Fill crankcase with new oil. Level should be at top of
indicator on dipstick.
7. Reinstall oil fi ll/dipstick and tighten securely.
8. Start engine; check for oil leaks. Stop engine; correct
leaks. Recheck oil level.
9. Dispose of used oil and fi lter in accordance with
local ordinances.
A
B
C
A
A Oil Fill/Dipstick B Oil Drain Plug C Oil Filter
This engine uses a combination pressure/splash lubrication system, delivering oil under pressure to crankshaft,
connecting rod and main bearing surfaces. Other component areas are splash lubricated.
A high-effi ciency gerotor oil pump maintains high oil fl ow and oil pressure, even at low speeds and high operating
temperatures. A pressure relief valve limits maximum pressure of system. Oil pan must be removed to service oil
pickup and oil pump.
Lubrication Components
52
Lubrication System
KohlerEngines.com 32 690 03 Rev. M
OIL SENTRY
™
(if equipped)
NOTE: Make sure oil level is checked before each use,
and is maintained up to FULL or F mark on
dipstick. This includes engines equipped with
Oil Sentry
™
.
This switch is designed to prevent engine from starting in
a low oil or no oil condition. Oil Sentry
™
may not shut
down a running engine before damage occurs. In some
applications this switch may activate a warning signal.
Read your equipment manuals for more information.
Oil Sentry
™
pressure switch is installed in oil fi lter
adapter. Pressure switch is designed to break contact as
oil pressure increases above 3-5 psi, and make contact
as oil pressure decreases below 3-5 psi.
On stationary or unattended applications (pumps,
generators, etc.), pressure switch can be used to ground
ignition module to stop engine. On vehicular applications
(lawn tractors, mowers, etc.) pressure switch can only be
used to activate a low oil warning light or signal.
Installation
1. Apply pipe sealant with Tefl on
®
(Loctite
®
PST
®
592™
Thread Sealant or equivalent) to threads of switch.
2. Install switch into tapped hole in oil fi lter adapter.
3. Torque switch to 4.5 N·m (40 in. lb.).
Testing
Compressed air, a pressure regulator, pressure gauge,
and a continuity tester are required to test switch.
1. Connect continuity tester across blade terminal and
metal case of switch. With 0 psi pressure applied to
switch, tester should indicate continuity (switch
closed).
2. Gradually increase pressure to switch. As pressure
increases through range of 2-5 psi tester should
indicate a change to no continuity (switch open).
Switch should remain open as pressure is increased
to 90 psi maximum.
3. Gradually decrease pressure through range of
2-5 psi. Tester should indicate a change to continuity
(switch closed) down to 0 psi.
4. Replace switch if it does not operate as specifi ed.
Electrical System
5332 690 03 Rev. M KohlerEngines.com
SPARK PLUGS
CAUTION
Electrical Shock can cause injury.
Do not touch wires while engine is running.
Spark Plug Component and Details
B
A
C
D
A Wire Gauge B Spark Plug
C Ground Electrode D Gap
NOTE: Do not clean spark plug in a machine using
abrasive grit. Some grit could remain in spark
plug and enter engine causing extensive wear
and damage.
Engine misfi re or starting problems are often caused
by a spark plug that has improper gap or is in poor
condition.
Engine is equipped with following spark plugs:
Gap 0.76 mm (0.030 in.)
Thread Size 14 mm
Reach 19.1 mm (3/4 in.)
Hex Size 15.9 mm (5/8 in.)
Refer to Maintenance for Repairs/Service Parts.
Service
Clean out spark plug recess. Remove plug and replace.
1. Check gap using wire feeler gauge. Adjust gap to
0.76 mm (0.030 in.).
2. Install plug into cylinder head.
3. Torque plug to 27 N·m (20 ft. lb.).
Inspection
Inspect each spark plug as it is removed from cylinder
head. Deposits on tip are an indication of general
condition of piston rings, valves, and carburetor.
Normal and fouled plugs are shown in following photos:
Normal
Plug taken from an engine operating under normal
conditions will have light tan or gray colored deposits. If
center electrode is not worn, plug can be set to proper
gap and reused.
Worn
On a worn plug, center electrode will be rounded and
gap will be greater than specifi ed gap. Replace a worn
spark plug immediately.
Wet Fouled
A wet plug is caused by excess fuel or oil in combustion
chamber. Excess fuel could be caused by a restricted air
cleaner, a carburetor problem, or operating engine with
too much choke. Oil in combustion chamber is usually
caused by a restricted air cleaner, a breather problem,
worn piston rings, or valve guides.
Electrical System
54 32 690 03 Rev. MKohlerEngines.com
Carbon Fouled
Soft, sooty, black deposits indicate incomplete
combustion caused by a restricted air cleaner, over rich
carburetion, weak ignition, or poor compression.
Overheated
Chalky, white deposits indicate very high combustion
temperatures. This condition is usually accompanied
by excessive gap erosion. Lean carburetor settings,
an intake air leak, or incorrect spark timing are normal
causes for high combustion temperatures.
BATTERY
A 12-volt battery with 400 cold cranking amps (cca) is
generally recommended for starting in all conditions. A
smaller capacity battery is often suffi cient if an
application is started only in warmer temperatures. Refer
to following table for minimum capacities based on
anticipated ambient temperatures. Actual cold cranking
requirement depends on engine size, application, and
starting temperatures. Cranking requirements increase
as temperatures decrease and battery capacity shrinks.
Refer to equipment's operating instructions for specifi c
battery requirements.
Battery Size Recommendations
Temperature Battery Required
Above 32°F (0°C) 200 cca minimum
0°F to 32°F (-18°C to 0°C) 250 cca minimum
-5°F to 0°F (-21°C to -18°C) 300 cca minimum
-10°F (-23°C) or below 400 cca minimum
If battery charge is insuffi cient to turn over engine,
recharge battery.
Battery Maintenance
Regular maintenance is necessary to prolong battery
life.
Battery Test
To test battery, follow manufacturer's instructions.
ELECTRONIC IGNITION SYSTEMS
All ignition systems are designed to be trouble free for
life of engine. Other than periodically checking/replacing
spark plugs, no maintenance or timing adjustments
are necessary or possible. Mechanical systems do
occasionally fail or break down. Refer to Troubleshooting
to determine root of a reported problem.
Reported ignition problems are most often due to poor
connections. Before beginning test procedure, check
all external wiring. Be certain all ignition-related wires
are connected, including spark plug leads. Be certain all
terminal connections fi t snugly. Make sure ignition switch
is in run position.
Electrical System
5532 690 03 Rev. M KohlerEngines.com
Ignition Systems
These systems use a capacitive discharge (CD) coil. With CDI fi xed timing, ignition timing and spark remains constant
regardless of engine speed. Timing of spark is controlled by location of fl ywheel magnet group as referenced to
engine TDC. MDI adjustable timing uses a digital microprocessor which is located in ignition modules. Ignition timing
varies depending upon engine speed with this system.
A typical fi xed ignition system consists of:
● 1 magnet assembly which is permanently affi xed to fl ywheel.
● 2 electronic capacitive-discharge or magnetic discharge ignition modules which mount on engine crankcase.
● 1 kill switch (or key switch) which grounds modules to stop engine.
● 2 spark plugs.
Wiring Diagram-Electronic Ignition System Diagram
H
Q
L
G
AD
D
D
S
T
H
M
K
F
D
J
I
G
E
C
B
A
U
V
W
X
Y
Z
S
R
P
Q
Q
N
O
AA
AB
AE
AF
AF
AC
AB
AC
AG
A Starter Solenoid Tang B
Solenoid Shift
Starter Assembly
C
Inertia Driver
Starter Assembly
D Green
E Violet (Charging) F Oil Sentry
TM
(Optional) G Spark Plug(s) H
White
(AC Charging Leads)
I
Rectifi er-Regulator
Connector
J Rectifi er-Regulator K
Flywheel Stator
Assembly
L Ignition Module(s)
M Intake Manifold Screw N Ground O Carburetor P White (Ignition Kill)
Q Red R Solenoid Lead S Orange T Connector
U Blue V Starter Solenoid Stud W Relay Stud X
Relay Cranking
(Customer Supplied)
Y Battery Negative Z Battery AA Battery Positive AB
Violet (shown)
or Orange
AC White AD
Orange (shown)
or Red
AE Blue (shown) or Red AF Polarity Rib
AG
Solenoid Shift Starter
Assembly (Optional)
Electrical System
56 32 690 03 Rev. MKohlerEngines.com
Wiring Diagram-Electronic Ignition System with Original Design Smart-Choke
™
System
H
Q
L
G
AD
D
D
S
T
H
M
K
F
D
J
I
G
E
C
B
A
U
V
W
X
Y
Z
S
R
P
Q
Q
N
O
AA
AB
AE
AF
AF
AC
AB
AC
AG
AH
AJ
AI
A Starter Solenoid Tang B
Solenoid Shift
Starter Assembly
C
Inertia Driver
Starter Assembly
D Green
E Violet (Charging) F
Oil Sentry
TM
(3-Terminal Switch)
G Spark Plug(s) H
White
(AC Charging Leads)
I
Rectifi er-Regulator
Connector
J Rectifi er-Regulator K
Flywheel Stator
Assembly
L Ignition Module(s)
M Intake Manifold Screw N Ground O Carburetor P White (Ignition Kill)
Q Red R Solenoid Lead S Orange T Connector
U Blue V Starter Solenoid Stud W Relay Stud X
Relay Cranking
(Customer Supplied)
Y Battery Negative Z Battery AA Battery Positive AB
Violet (shown)
or Orange
AC White AD
Orange (shown)
or Red
AE Blue (shown) or Red AF Polarity Rib
AG
Solenoid Shift Starter
Assembly (Optional)
AH Thermostat Assembly AI Red AJ Red w/Black Line
Electrical System
5732 690 03 Rev. M KohlerEngines.com
Wiring Diagram-Electronic Ignition System with Updated Design Smart-Choke
™
System*
H
Q
L
G
AD
D
D
S
T
H
M
K
F
D
J
I
G
C
B
A
U
V
W
X
Y
Z
S
R
P
Q
Q
N
O
AA
AB
AE
AF
AF
AC
AB
AC
AG
AI
E
AH
AJ
A Starter Solenoid Tang B
Solenoid Shift
Starter Assembly
C
Inertia Driver
Starter Assembly
D Green
E Violet (Charging) F
Oil Sentry
TM
(Optional
1-Terminal Switch)
G Spark Plug(s) H
White
(AC Charging Leads)
I
Rectifi er-Regulator
Connector
J Rectifi er-Regulator K
Flywheel Stator
Assembly
L Ignition Module(s)
M Intake Manifold Screw N Ground O Carburetor P White (Ignition Kill)
Q Red R Solenoid Lead S Orange T Connector
U Blue V Starter Solenoid Stud W Relay Stud X
Relay Cranking
(Customer Supplied)
Y Battery Negative Z Battery AA Battery Positive AB
Violet (shown)
or Orange
AC White AD
Orange (shown)
or Red
AE Blue (shown) or Red AF Polarity Rib
AG
Solenoid Shift Starter
Assembly (Optional)
AH Thermostat Assembly AI Fuse AJ Red w/Black Line
*For engines with eChoke
™
, refer to component illustrations in Fuel Section of this manual.
Electrical System
58 32 690 03 Rev. MKohlerEngines.com
Electronic Ignition Systems Tests
NOTE: Ignition tester must be used to test ignition on these engines. Use of any other tester can result in inaccurate
fi ndings. Battery on unit must be fully charged and properly connected before performing tests (a battery that
is hooked up or charged backward will crank engine but it won’t have spark). Be certain drive is in neutral and
all external loads are disconnected.
Test Ignition Systems
NOTE: If engine starts or runs during testing, you may need to ground kill lead to shut it down. Because you have
interrupted kill circuit, it may not stop using switch.
Isolate and verify trouble is within engine.
1. Locate connectors where wiring harnesses from engine and equipment are joined. Separate connectors and
remove white kill lead from engine connector. Rejoin connectors and position or insulate kill lead terminal so it
cannot touch ground. Try to start engine to verify whether reported problem is still present.
Condition Possible Cause Conclusion
Problem goes away. Electrical System Check key switch, wires, connections,
safety interlocks, etc.
Problem persists. Ignition or Electrical System Leave kill lead isolated until all testing
is completed.
Identify white kill lead of engine
wiring harness connector. Establish
a connection to a known good
ground location. Engine should kill
completely. If not or only one cylinder
is aff ected, test ignition modules.
Test for Spark
NOTE: If 2 testers are available, testing can be performed simultaneously for both cylinders. However, if only 1 tester
is available, 2 individual tests must be performed. Side not being tested must have spark plug lead connected
or grounded. Do not crank engine or perform tests with 1 spark plug lead disconnected and not grounded, or
permanent system damage may occur.
1. With engine stopped, disconnect 1 spark plug lead. Connect spark plug lead to post terminal of spark tester and
attach tester clip to a good engine ground.
2. Crank engine over, establishing a minimum of 550-600 RPM, and observe tester(s) for spark.
3. Repeat spark test on opposite cylinder if cylinders are being tested individually.
Condition Possible Cause Conclusion
One side is not fi ring. Wiring and Connections Check all wiring, connections, and
terminals on that side. If wiring is
okay, replace ignition module and
retest for spark.
Tester shows spark but engine
misses or won’t run on that cylinder.
Spark Plug(s) Try new spark plug(s).
Neither side is fi ring. Ignition Switch Recheck position of ignition switch
and check for shorted kill lead.
Both cylinders have good spark but
engine runs poorly or existing plug
condition is questionable.
Spark Plug(s) Install new spark plug(s) and retest
engine performance.
1 cylinder has good spark and other
cylinder has no or intermittent spark.
Ignition Test ignition modules and
connections.
Electrical System
5932 690 03 Rev. M KohlerEngines.com
BATTERY CHARGING SYSTEM
NOTE: Observe following guidelines to avoid damage to electrical system and components:
● Make sure battery polarity is correct. A negative (–) ground system is used.
● Disconnect rectifi er-regulator plug and/or wiring harness plug before doing any electric welding on equipment
powered by engine. Disconnect all other electrical accessories in common ground with engine.
● Prevent stator (AC) leads from touching or shorting while engine is running. This could damage stator.
Most engines are equipped with a 12/15 amp regulated charging system. Some have a 25 amp regulated charging
system.
12/15/25 Amp Regulated Charging System
Stator
Stator is mounted on crankcase behind fl ywheel. Follow procedures in Disassembly and Reassembly if stator
replacement is necessary.
Rectifi er-Regulator
NOTE: When installing rectifi er-regulator, take note of terminal positions and install plug correctly.
NOTE: Disconnect all electrical connections attached to rectifi er-regulator. Testing may be performed with rectifi er-
regulator mounted or loose. Repeat applicable test procedure 2 or 3 times to determine condition of part.
Rectifi er-regulator is mounted on backing shroud assembly. To replace it, disconnect plug, remove mounting screws,
and ground lead.
Testing rectifi er-regulator may be performed as follows, using appropriate rectifi er-regulator tester.
To test 25 amp rectifi er-regulators:
1. Connect single lead adapter in between B+ (center)
terminal of rectifi er-regulator being tested and
squared single end of tandem adapter lead.
2. Connect tester ground lead (with spring clamp) to
body of rectifi er-regulator.
3. Connect red lead and 1 black lead to terminals on
open end of tandem adapter lead (connections are
not location specifi c).
4. Connect remaining black lead from tester to 1 outer
AC terminal on rectifi er-regulator.
5. Plug tester into proper AC outlet/power for tester
being used. Turn on power switch. POWER light
should be illuminated and 1 of 4 status lights may be
on as well. This does not represent condition of part.
6. Press TEST button until a click is heard and then
release. Momentarily 1 of 4 lights will illuminate
indicating partial condition of part.
To test 12/15 amp rectifi er-regulators:
1. Connect tester ground lead (with spring clamp) to
body of rectifi er-regulator being tested.
2. Connect tester red lead to B+ terminal of rectifi er-
regulator and 2 black tester leads to 2 AC terminals.
3. Plug tester into proper AC outlet/power for tester
being used. Turn on power switch. POWER light
should be illuminated and 1 of 4 status lights may be
on as well. This does not represent condition of part.
4. Press TEST button until a click is heard and then
release. Momentarily 1 of 4 status lights will
illuminate indicating condition of part.
Condition Conclusion
25 amp 12/15 amp
OK (green) light comes on and stays steady. Disconnect tester black lead
attached to 1 AC terminal and
reconnect it to other AC terminal.
Repeat test. If OK (green) light
comes on again, part is good
and may be used.
Part is good and may be used.
NOTE: A fl ashing LOW light can also occur as
a result of an inadequate ground lead
connection. Make certain connection
location is clean and clamp is secure.
Other lights come on.
Rectifi er-regulator is faulty and should not be used.
Electrical System
60 32 690 03 Rev. MKohlerEngines.com
12/15/25 Amp Battery Charging Systems
NOTE: Always zero ohmmeter on each scale before testing to ensure accurate readings. Voltage tests should be
made with engine running at 3600 RPM with no load. Battery must be good and fully charged.
When problems occur in keeping battery charged or battery charges at high rate, charging system or battery might be
causing problems.
To test charging system for no charge to battery:
1. Insert an ammeter in B+ lead from rectifi er-regulator.
With engine running at 3600 RPM and B+ (at
terminal on rectifi er-regulator) to ground using a DC
voltmeter.
If voltage is 13.8 volts or more, place a minimum
load of 5 amps (turn on lights if 60 watts or more, or
place a 2.5 ohm, 100 watt resistor across battery
terminals) on battery to reduce voltage. Observe
ammeter.
Condition Conclusion
Charge rate increases
when load is applied.
Charging system is OK
and battery was fully
charged.
Charge rate does not
increase when load is
applied.
Test stator and rectifi er-
regulator (steps 2 and 3).
2. Remove connector from rectifi er-regulator. With
engine running at 3600 RPM, measure AC voltage
across stator leads using an AC voltmeter.
Condition Conclusion
Voltage is 28 volts or
more.
Stator is OK. Rectifi er-
regulator is faulty; replace.
Voltage is less than 28
volts.
Stator is faulty; replace.
Test stator further using an
ohmmeter (steps 3 and 4).
3. With engine stopped, measure resistance across
stator leads using an ohmmeter.
Condition Conclusion
Resistance is 0.064/0.2
ohms.
Stator is OK.
Resistance is 0 ohms. Stator is shorted; replace.
Resistance is infi nity
ohms.
Stator is open; replace.
4. With engine stopped, measure resistance from each
stator lead to ground using an ohmmeter.
Condition Conclusion
Resistance is infi nity ohms
(no continuity).
Stator is OK (not shorted
to ground).
Resistance (or continuity)
measured.
Stator leads are shorted to
ground; replace.
To test charging system for battery continuously charging
at high rate:
1. With engine running at 3600 RPM, measure voltage
from B+ lead to ground using a DC voltmeter.
Condition Conclusion
Voltage is 14.7 volts or
less.
Charging system is OK.
Battery is unable to hold
charge; service or replace.
Voltage is more than 14.7
volts.
Faulty rectifi er-regulator;
replace.
Starter System
6132 690 03 Rev. M KohlerEngines.com
NOTE: Do not crank engine continuously for more than 10 seconds. Allow a 60 second cool-down period between
starting attempts. Failure to follow these guidelines can burn out starter motor.
NOTE: If engine develops suffi cient speed to disengage starter but does not keep running (a false start), engine
rotation must be allowed to come to a complete stop before attempting to restart engine. If starter is engaged
while fl ywheel is rotating, starter pinion and fl ywheel ring gear may clash and damage starter.
NOTE: If starter does not crank engine, shut off starter immediately. Do not make further attempts to start engine until
condition is corrected.
NOTE: Do not drop starter or strike starter frame. Doing so can damage starter.
Engines in this series use inertia drive or solenoid shift starters. Inertia drive electric starters are not serviceable
Troubleshooting-Starting Diffi culties
Condition Possible Cause Conclusion
Starter does not energize. Battery Check specifi c gravity of battery. If low, recharge or replace
battery as necessary.
Wiring Clean corroded connections and tighten loose connections.
Replace wires in poor condition and with frayed or broken
insulation.
Starter Switch
or Solenoid
By-pass switch or solenoid with a jumper wire. If starter cranks
normally, replace faulty components. Remove and perform
individual solenoid test procedure.
Starter energizes but turns
slowly.
Battery Check specifi c gravity of battery. If low, recharge or replace
battery as necessary.
Brushes Check for excessively dirty or worn brushes and commutator.
Clean using a coarse cloth (not emery cloth).
Replace brushes if excessively or unevenly worn.
Transmission
or Engine
Make sure clutch or transmission is disengaged or placed
in neutral. This is especially important on equipment with
hydrostatic drive. Transmission must be exactly in neutral to
prevent resistance which could keep engine from starting.
Check for seized engine components such as bearings,
connecting rod, and piston.
INERTIA DRIVE ELECTRIC STARTERS
When power is applied to starter, armature rotates. As armature rotates, drive pinion moves out on drive shaft splines
and into mesh with fl ywheel ring gear. When pinion reaches end of drive shaft, it rotates fl ywheel and cranks engine.
When engine starts, fl ywheel rotates faster than starter armature and drive pinion. This moves drive pinion out of
mesh with ring gear and into retracted position. When power is removed from starter, armature stops rotating and
drive pinion is held in retracted position by anti-drift spring.
Starter System
62 32 690 03 Rev. MKohlerEngines.com
SOLENOID SHIFT STARTERS
Solenoid Shift Starter Components
A
B
U
T
S
R
Q
P
O
N
M
L
K
J
I
H
G
F
E
D
C
A Tube B Washer
C Armature D Drive
E Stop F Retaining Ring
G Collar H Drive End Cap
I Screw J Plunger
K Spring L Lever
M Plate N Plug
O Solenoid P Frame and Field
Q Brush Holder R Nut
S
Commutator End
Plate
T Screw
U Bolt
When power is applied to starter electric solenoid moves
drive pinion out onto drive shaft and into mesh with
fl ywheel ring gear. When pinion reaches end of drive
shaft it rotates fl ywheel and cranks engine.
When engine starts and start switch is released, starter
solenoid is deactivated, drive lever moves back, and
drive pinion moves out of mesh with ring gear into
retracted position.
Starter Disassembly
NOTE: Do not reuse old retainer.
NOTE: Do not soak armature or use solvent when
cleaning. Wipe clean using a soft cloth, or use
compressed air.
1. Remove hex nut and disconnect positive (+) brush
lead/bracket from solenoid terminal.
2. Remove head screws securing solenoid to starter.
3. Unhook plunger pin from drive lever. Remove gasket
from recess in housing.
4. Remove thru (larger) bolts.
5. Remove commutator end plate assembly, containing
brush holder, brushes, springs, and locking caps.
Remove thrust washer from inside commutator end.
6. Remove frame from armature and drive end cap.
7. Remove drive lever pivot bushing and backing plate
(if equipped) from end cap.
8. Take out drive lever and pull armature out of drive
end cap.
9. Remove thrust washer from armature shaft.
10. Push stop collar down to expose retaining ring.
11. Remove retainer from armature shaft. Save stop
collar.
12. Remove drive pinion assembly from armature.
13. Clean parts as required.
Inspection
Drive Pinion
Check and inspect following areas:
● Pinion teeth for abnormal wear or damage.
● Surface between pinion and clutch mechanism for
nicks or irregularities which could cause seal damage.
● Check drive clutch by holding clutch housing and
rotating pinion. Pinion should rotate in only 1 direction.
Brushes and Springs
Detail
A
A Wear Limit Length
Inspect both springs and brushes for wear, fatigue, or
damage. Measure length of each brush. Minimum length
for each brush is 7.6 mm (0.300 in.). Replace brushes if
they are worn, undersize, or condition is questionable.
Starter System
6332 690 03 Rev. M KohlerEngines.com
Armature
Components and Details
A
B
A Commutator O.D. B Mica Insulation
D
E
C
C Insulation Check D Armature Coil
E Continuity Check
1. Clean and inspect commutator (outer surface). Mica
insulation must be lower than commutator bars
(undercut) to ensure proper operation of
commutator.
2. Use an ohmmeter set to Rx1 scale. Touch probes
between 2 diff erent segments of commutator, and
check for continuity. Test all segments. Continuity
must exist between all or armature is bad.
3. Check for continuity between armature coil
segments and commutator segments. There should
be no continuity. If continuity exists between any 2
armature is bad.
4. Check armature windings/insulation for shorting.
Shift Fork
Check that shift fork is complete, and pivot and contact
areas are not excessively worn, cracked, or broken.
Brush Replacement
4 brushes and springs are serviced as a set. Use a new
Kohler brush and spring kit if replacement is necessary.
1. Perform steps 1-5 in Starter Disassembly.
2. Remove screws securing brush holder assembly to
end cap (plate). Note orientation for reassembly later.
Discard old brush holder assembly.
3. Clean component parts as required.
New brushes and springs come preassembled in a
brush holder with a protective sleeve that will also
serve as an installation tool.
4. Perform steps 10-13 in Starter Reassembly
sequence. If starter has been disassembled,
installation must be done after armature, drive lever,
and frame are installed.
Starter Reassembly
NOTE: Always use a new retainer. Do not reuse old
retainers that have been removed.
NOTE: Correctly installed, center pivot section of drive
lever will be fl ush or below machined surface of
housing.
1. Apply drive lubricant to armature shaft splines. Install
drive pinion onto armature shaft.
2. Install and assemble stop collar/retainer assembly.
a. Install stop collar down onto armature shaft with
counter bore (recess) up.
b. Install a new retainer in larger (rear) groove of
armature shaft. Squeeze with a pliers to
compress it in groove.
c. Slide stop collar up and lock it into place, so
recess surrounds retainer in groove. If necessary,
rotate pinion outward on armature splines against
retainer to help seat collar around retainer.
3. Install off set thrust (stop) washer so smaller off set of
washer faces retainer/collar.
4. Apply a small amount of oil to bearing in drive end
cap, and install armature with drive pinion.
5. Lubricate fork end and center pivot of drive lever
with drive lubricant. Position fork end into space
between captured washer and rear of pinion.
6. Slide armature into drive end cap and at same time
seat drive lever into housing.
7. Install rubber grommet into matching recess of drive
end cap. Molded recesses in grommet should be
out, matching and aligned with those in end cap.
8. Install frame, with small notch forward, onto
armature and drive end cap. Align notch with
corresponding section in rubber grommet. Install
drain tube in rear cutout, if it was removed
previously.
9. Install fl at thrust washer onto commutator end of
armature shaft.
10. Starter reassembly when replacing brushes/brush
holder assembly:
a. Hold starter assembly vertically on end housing,
and carefully position assembled brush holder
assembly, with supplied protective tube, against
end of commutator/armature. Mounting screw
holes in metal clips must be up/out. Slide brush
holder assembly down into place around
commutator, and install positive (+) brush lead
grommet in cutout of frame. Protective tube may
be saved and used for future servicing.
Starter reassembly when not replacing brushes/
brush holder assembly:
a. Carefully unhook retaining caps from brush
assemblies. Do not lose springs.
b. Position brushes back in their slots so they are
fl ush with I.D. of brush holder assembly. Insert
brush installation tool (with extension), or use
tube described above from a prior brush
installation, through brush holder assembly, so
holes in metal mounting clips are up/out.
Starter System
64 32 690 03 Rev. MKohlerEngines.com
c. Install brush springs and snap on retainer caps.
d. Hold starter assembly vertically on end housing, and carefully place tool (with extension) and assembled
original brush holder assembly onto end of armature shaft. Slide brush holder assembly down into place
around commutator, install positive (+) brush lead grommet in cutout of frame.
11. Install end cap onto armature and frame, aligning thin raised rib in end cap with corresponding slot in grommet of
positive (+) brush lead.
12. Install thru bolts and brush holder mounting screws. Torque bolts to 5.6-9.0 N·m (49-79 in. lb.) and brush holder
mounting screws to 2.5-3.3 N·m (22-29 in. lb.).
13. Hook plunger behind upper end of drive lever and install spring into solenoid. Insert mounting screws through
holes in drive end cap. Use these to hold solenoid gasket in position, then mount solenoid. Torque screws to
4.0-6.0 N·m (35-53 in. lb.).
14. Connect positive (+) brush lead/bracket to solenoid and secure with nut. Torque nut to 8-11 N·m (71-97 in. lb.). Do
not overtighten.
Solenoid Tests
NOTE: DO NOT leave 12 volt test leads connected to solenoid for any time over what is necessary for performing
each of individual tests. Internal damage to solenoid may occur.
Disconnect all leads from solenoid including positive brush lead attached to lower stud terminal. Remove mounting
hardware and separate solenoid from starter for testing.
To test solenoid pull-in coil/plunger:
Actuation
1. Use a 12 volt power supply and 2 test leads.
2. Connect 1 lead to fl at spade S/start terminal on solenoid. Momentarily connect other lead to lower large post
terminal.
When connection is made solenoid should energize (audible click) and plunger retract. Repeat test several times.
Continuity
1. Use an ohmmeter set to audible or Rx2K scale, and connect 2 ohmmeter leads to 2 large post terminals.
2. Perform solenoid pull-in coil/plunger actuation test and check for continuity. Ohmmeter should indicate continuity.
Repeat test several times.
To test solenoid hold-in coil:
Function
1. Connect a 12 volt test lead to fl at spade S/start terminal on solenoid and other lead to body or mounting surface of
solenoid.
2. Manually push plunger IN and check if coil holds plunger retracted. Do not allow test leads to remain connected to
solenoid for a prolonged period of time.
Continuity
1. Use an ohmmeter set to audible or Rx2K scale, and connect 2 ohmmeter leads to 2 large post terminals.
2. Perform preceding solenoid hold-in coil function test and check for continuity. Meter should indicate continuity.
Repeat test several times.
Condition Conclusion
Solenoid fails to activate. Replace solenoid.
No continuity is indicated.
Plunger fails to stay retracted.
65
Emission Compliant Systems
32 690 03 Rev. M KohlerEngines.com
EVAPORATIVE EMISSION COMPLIANT SYSTEM
Carbon Canister System
A Fuel Tank Cap B Fuel Tank C
Roll Over Valve
(ROV)
D Carbon Canister
E
Canister Breather
Filter
F To Carburetor
A
B
C
D
E
F
Operation
Fuel vapors travel from fuel tank through tubing to
carbon canister. On intake stroke of engine fuel vapors
are drawn in through a port in carburetor and burned
with fuel charge.
Maintenance
On Kohler-supplied canisters, breather fi lter can be
removed and cleaned with hot soapy water, dried and
reinstalled. Do not oil breather screen. This is done
periodically or if system operation is suspect. Carbon
canister is sealed and requires no maintenance.
In some applications or installations, OEM will have
installed a diff erent canister or fuel vapor recovery
system. See OEM equipment documentation for service
or maintenance information.
For engine to be Tier III compliant, it may be fi tted with a Kohler supplied canister vapor recovery system, or a system
developed and installed by Original Equipment Manufacturer (OEM). Details on Kohler system are included below.
66
Emission Compliant Systems
KohlerEngines.com 32 690 03 Rev. M
SECONDARY EMISSION COMPLIANT SYSTEM
Twin Secondary Air Induction System
A
Hose To Exhaust
Manifold
B Inlet Screen C
Secondary Air
Valve Assembly
D Hose To Carburetor
E
Hose To Exhaust
Manifold
Single Secondary Air Induction System
F
Secondary Air
Valve Assembly
G
Hose To Exhaust
Manifold
H Hose To Carburetor I Inlet Screen
A
B
C
D
C
E
F
G
F
H
I
Operation
Intake pulse of engine activates secondary air valve.
Air is drawn through an inlet screen of secondary air
valve. Air is then drawn into exhaust manifold and
muffl er where it mixes with any unburned hydrocarbons,
which then burn in heat of muffl er. A hose is connected
between a carburetor port and a diaphragm chamber
in secondary air valve. Carburetor vacuum moves
diaphragm to close valve when air induction is not
required, primary idle.
Maintenance
Air inlet screen in secondary air valve can be removed,
cleaned, and reinstalled. If inspection of system reveals
any damage or decomposition of hoses, secondary air
valve, or exhaust system, parts should be replaced.
For engine to be Tier III compliant, it may be fi tted with a secondary air induction system (SAI).
67
Emission Compliant Systems
32 690 03 Rev. M KohlerEngines.com
Remove Inlet Screen
Inlet Components
A
B
C
A Secondary Air Valve Assembly B Barb C Inlet Screen
1. Remove inlet screen from secondary air valve assembly by grasping inlet screen at base and gently pulling away
from valve assembly.
2. Use a soft brush to remove debris from screen.
3. Run water through inlet screen in reverse direction.
4. To reinstall, push inlet screen onto barb of secondary air valve assembly. An audible click will be heard when inlet
screen is properly reinstalled.
68
Disassembly/Inspection and Service
KohlerEngines.com 32 690 03 Rev. M
WARNING
Before working on engine or equipment, disable engine as
follows: 1) Disconnect spark plug lead(s). 2) Disconnect
negative (–) battery cable from battery.
Accidental Starts can cause severe injury or
death.
Disconnect and ground spark plug lead(s)
before servicing.
External Engine Components
J
T
E
L
G
S
R
E
E
F
H
H
I
V
U
K
B
A
C
D
M
O
N
P
Q
W
R
S
B
S
B
A Fixed Guard B Air Cleaner Cover C Debris Screen D Blower Housing
E Hose Clamp F Fuel Pump G Hose Clip H Fuel Line
I Fuel Filter J Oil Filter K Outer Baffl e L Electric Starter
M Inner Baffl e N Ignition Module O Intake Manifold P Carburetor
Q Gasket R Air Cleaner Base S Air Cleaner Element T Rectifi er-Regulator
U Dipstick Tube V Oil Fill/Dipstick W Breather Hose
69
Disassembly/Inspection and Service
32 690 03 Rev. M KohlerEngines.com
Clean all parts thoroughly as engine is disassembled.
Only clean parts can be accurately inspected
and gauged for wear or damage. There are many
commercially available cleaners that will quickly remove
grease, oil and grime from engine parts. When such a
cleaner is used, follow manufacturer’s instructions and
safety precautions carefully.
Make sure all traces of cleaner are removed before
engine is reassembled and placed into operation. Even
small amounts of these cleaners can quickly break down
lubricating properties of engine oil.
Disconnect Spark Plug Leads
NOTE: Pull on boot only, to prevent damage to spark
plug lead.
1. Disconnect leads from spark plugs.
2. Shut off fuel supply.
Drain Oil From Crankcase and Remove Oil Filter
1. Remove oil fi ll/dipstick and oil drain plug.
2. Allow ample time for oil to drain from crankcase and
oil fi lter.
3. Remove and appropriately discard oil fi lter.
Remove Muffl er
Remove exhaust system and attaching hardware from
engine.
Remove Fuel Pump (if equipped)
WARNING
Explosive Fuel can cause fi res and severe
burns.
Do not fi ll fuel tank while engine is hot or
running.
Gasoline is extremely fl ammable and its vapors can
explode if ignited. Store gasoline only in approved
containers, in well ventilated, unoccupied buildings,
away from sparks or fl ames. Spilled fuel could ignite
if it comes in contact with hot parts or sparks from
ignition. Never use gasoline as a cleaning agent.
1. Disconnect pulse (vacuum) hose and outlet fuel line
from fuel pump.
2. Remove mounting screws, unhook outlet hose from
blower housing clip, and remove fuel pump from
blower housing.
Remove Blower Housing and Outer Baffl es
1. Remove air cleaner cover.
2. Remove screws securing blower housing.
3. Remove blower housing from engine.
4. Remove M5 and M6 screws securing baffl es to
cylinders, heads and backing plate.
Remove Throttle Controls
Control Bracket Components
F
G
C
C
C
B
A
D
D
E
A Choke Linkage B Throttle Linkage
C Governor Lever D Governor Spring
E Cross Shaft F Control Bracket
G Dampener Spring
1. Remove screws securing throttle control bracket to
cylinder heads.
2. Disconnect choke linkage from choke actuator lever.
Unhook governor spring, and dampener spring from
governor lever. Note hole locations for reassembly.
Remove External Governor Controls
Loosen nut and remove governor lever from cross shaft.
Leave lever attached to throttle linkage.
70
Disassembly/Inspection and Service
KohlerEngines.com 32 690 03 Rev. M
Remove Air Cleaner and Carburetor
WARNING
Explosive Fuel can cause fi res and severe
burns.
Do not fi ll fuel tank while engine is hot or
running.
Gasoline is extremely fl ammable and its vapors can
explode if ignited. Store gasoline only in approved
containers, in well ventilated, unoccupied buildings,
away from sparks or fl ames. Spilled fuel could ignite
if it comes in contact with hot parts or sparks from
ignition. Never use gasoline as a cleaning agent.
Smart-Choke
™
and eChoke
™
Carburetor/Air Cleaner
Components
A
B
F
C
D
E
A
G
D
H
A Air Cleaner Base B Breather Hose
C Ground Lead D Solenoid Lead
E
Smart-Choke
™
Bracket Assembly
F Thermostat
G
eChoke
™
Bracket
Assembly
H Stepper Motor
NOTE: On engines equipped with eChoke
™,
stepper
motor has a special retract routine that can be
activated to ensure motor is in correct position
prior to removal or upon replacement of stepper
motor when a problem is shown to exist with
stepper motor assembly and carburetor.
Activation of this routine will occur by initiating
three (3) consecutive Key On–Off cycles. Every
Key On and Off should be > 2 seconds and <
3.5 seconds. Note that if no other connections
are disturbed, stepper motor will be repositioned
at next key ON and master module will go back
to normal choke operation mode.
NOTE: Do not remove or loosen thermostat screws.
Position is set at factory.
1. Remove carburetor/air cleaner base mounting nuts
and disconnect breather hose.
2. Remove air cleaner element and precleaner (if
equipped) from air cleaner base for servicing.
3. Disconnect ground lead and fuel shut-off solenoid
lead (if equipped).
4. Remove Smart-Choke
™
or eChoke
™
bracket
assembly (if equipped). Remove air cleaner base
and gasket.
5. Remove carburetor, throttle linkage and governor
lever as an assembly.
6. Remove carburetor gasket.
7. If necessary, carburetor, throttle linkage and
governor lever can be separated. Reattach bushings
to linkage following separation to avoid losing them.
Remove Electric Starter Motor
1. Disconnect leads from starter.
2. Remove screws and starter.
Remove Inner Baffl es
Remove mounting screws securing inner baffl es to
crankcase. Note position of any lifting bracket(s).
Remove inner baffl es.
Remove Ignition Modules
NOTE: Some early production engines equipped with
Smart-Choke
™
have a defl ector support tab on
#2 cylinder ignition module. If equipped, note
position for reassembly.
1. Rotate fl ywheel so magnet is away from modules.
2. Disconnect lead from each ignition module.
3. Remove mounting screws and ignition modules.
Note position of ignition modules.
71
Disassembly/Inspection and Service
32 690 03 Rev. M KohlerEngines.com
Remove Intake Manifold and Rectifi er-Regulator
1. Remove screws securing intake manifold to cylinder
heads. Note which screws hold wiring clamp(s).
2. On engines equipped with Smart-Choke
™
,
disconnect choke unloader linkage from carburetor.
Unless air vane defl ector is damaged or
malfunctioning, disassembly from intake manifold is
not necessary.
3. Remove intake manifold and O-rings. Leave wiring
harness attached to manifold.
Cylinder Head Components
A
B
C
I
E
F
G
H
D
K
L
M
N
J
P
O
M
R
Q
N
A Gasket B Valve C Cylinder Head D Valve Spring Cap
E Valve Stem Seal F Valve Spring G Valve Spring Keeper H Stud
I Spark Plug J Guide Plate K Push Rod L Rocker Arm
M Rocker Arm Pivots N Adjusters O Washer P
Stamped Steel Valve
Cover (RTV)
Q
Plastic Valve Cover
(O-Ring)
R O-Ring
4. Remove screws securing rectifi er-regulator to
backing plate and disconnect plug.
5. Use tip of a small screwdriver or similar small fl at
tool to bend locking tang, then remove B+ (center
lead) from terminal plug. This will allow intake
manifold to be removed with wiring harness intact.
72
Disassembly/Inspection and Service
KohlerEngines.com 32 690 03 Rev. M
Remove Spark Plugs
Remove spark plug from each cylinder head.
Remove Valve Covers and Cylinder Heads
Plastic Valve Covers with O-Rings
Remove screws securing each valve cover. Most valve
covers have screw hole spacers molded in place.
Remove valve covers and O-rings.
Stamped Steel Valve Covers with RTV Sealant
NOTE: Valve cover is sealed to cylinder head using
RTV silicone sealant. When removing valve
cover, use care not to damage gasket surfaces
of cover and cylinder head. To break RTV seal,
hold a block of wood against 1 fl at face of valve
cover. Strike wood fi rmly with a mallet. If seal
doesn't break loose after 1 or 2 attempts, repeat
procedure on other side.
1. Remove Torx screws securing each valve cover.
2. Using a brass wire brush and gasket remover or
similar solvent, clean old RTV from surface of
cylinder head and valve cover.
3. Sealing surface of stamped steel valve covers must
be checked for fl atness prior to reinstallation. Hold
valve cover down fi rmly against a fl at, level surface
or piece of glass, and check around entire perimeter
that a 0.012 in. (0.30 mm) feeler gauge cannot be
inserted anywhere. If gauge goes in anywhere,
cover needs to be replaced.
Remove Cylinder Heads
NOTE: Exhaust side is located on output shaft side of
engine, while intake side is located on fan side
of engine. Cylinder head number is embossed
on outside of each cylinder head.
1. Loosen inner setscrews (T25 Torx), and back off
adjusters.
2. Mark location of push rods as either intake or
exhaust and cylinder 1 or 2. Push rods should
always be installed in same positions.
3. Remove screws securing each cylinder head.
4. Remove cylinder head and head gasket.
Disassemble Cylinder Heads
NOTE: Use a new valve stem seal whenever valve is
removed or if valve stem seal is deteriorated or
damaged. Never reuse an old valve stem seal.
1. Remove adjusters, pivots, rocker arms, studs and
guide plate from cylinder head.
2. Compress valve springs using a valve spring
compressor.
3. Once valve spring is compressed, remove following
items.
● Valve spring keepers.
● Valve spring caps.
● Valve springs.
● Intake and exhaust valves (mark position).
● Valve stem seal.
● Washer (intake valve only).
4. Repeat above procedure for other cylinder head. Do
not interchange parts from 1 cylinder head to
another.
73
Disassembly/Inspection and Service
32 690 03 Rev. M KohlerEngines.com
Inspection and Service
Valve Details
H
E
F
A
C
D
F
E
G
A
H
D
A
B
B
G
Intake Valve
Exhaust Valve
Intake Insert
Exhaust Insert
Dimension Intake Exhaust
A Seat Angle 89° 89°
B Insert O.D. 36.987/37.013 mm (1.4562/1.4572 in.) 32.987/33.013 mm (1.2987/1.2997 in.)
C Guide Depth 4 mm (0.1575 in.) 6.5 mm (0.2559 in.)
D Guide I.D. 7.040/7.060 mm (0.2772/0.2780 in.) 7.040/7.060 mm (0.2772/0.2780 in.)
E Valve Head Diameter 33.37/33.63 mm (1.3138/1.3240 in.) 29.37/29.63 mm (1.1563/1.1665 in.)
F Valve Face Angle 45° 45°
G Valve Margin (Min.) 1.5 mm (0.0591 in.) 1.5 mm (0.0591 in.)
H Valve Stem Diameter 6.982/7.000 mm (0.2749/0.2756 in.) 6.970/6.988 mm (0.2744/0.2751 in.)
After cleaning, check fl atness of cylinder head and corresponding top surface of crankcase, using a surface plate or
precision straight edge and feeler gauge. Maximum allowable out of fl atness is 0.076 mm (0.003 in.).
Carefully inspect valve mechanism parts. Inspect valve
springs and related hardware for excessive wear or
distortion. Check valves and valve seat area or inserts
for evidence of deep pitting, cracks, or distortion.
Check clearance of valve stems in guides. See valve
details and specifi cations.
Hard starting, or loss of power accompanied by high
fuel consumption may be symptoms of faulty valves.
Although these symptoms could also be attributed to
worn rings, remove and check valves fi rst. After removal,
clean valve heads, faces, and stems with a power wire
brush. Then, carefully inspect each valve for defects
such as warped head, excessive corrosion, or worn stem
end. Replace valves found to be in bad condition.
Valve Guides
If a valve guide is worn beyond specifi cations, it will not
guide valve in a straight line. This may result in burnt
valve faces or seats, loss of compression, and excessive
oil consumption.
To check valve guide-to-valve stem clearance,
thoroughly clean valve guide and, using a split-ball
gauge, measure inside diameter of guide. Then, using
an outside micrometer, measure diameter of valve stem
at several points on stem where it moves in valve guide.
Use largest stem diameter to calculate clearance by
subtracting stem diameter from guide diameter. If intake
clearance exceeds 0.040/0.078 mm (0.0016/0.0031 in.)
or exhaust clearance exceeds 0.052/0.090 mm
(0.0020/0.0035 in.), determine whether valve stem or
guide is responsible for excessive clearance.
Maximum (I.D.) wear on intake valve guide is 7.140 mm
(0.2811 in.) while 7.160 mm (0.2819 in.) is maximum
allowed on exhaust guide. Guides are not removable but
can be reamed 0.25 mm (0.010 in.) oversize. Valves with
0.25 mm oversize stems must then be used.
If guides are within limits but valve stems are worn
beyond limits, install new valves.
74
Disassembly/Inspection and Service
KohlerEngines.com 32 690 03 Rev. M
Flywheel/Ignition/Breather Components
I
K
L
J
M
F
G
H
C
B
A
D
E
A Flywheel Screw B Fan
C Washer D Fan Mounting Plate
E Magnet F Flywheel
G Stator H Backing Plate
I Breather Reed Cover J Stud
K Retainer L Breather Reed
M Flywheel Key
Valve Seat Inserts
Hardened steel alloy intake and exhaust valve seat
inserts are press-fi tted into cylinder head. Inserts are
not replaceable but can be reconditioned if not too badly
pitted or distorted. If cracked or badly warped, cylinder
head should be replaced.
Recondition valve seat inserts following instructions
provided with valve seat cutter being used. Final cut
should be made with an 89° cutter as specifi ed for
valve seat angle. Cutting proper 45° valve face angle,
as specifi ed, and proper valve seat angle (44.5°, half of
full 89° angle), will achieve desired 0.5° (1.0° full cut)
interference angle where maximum pressure occurs on
outside diameters of valve face and seat.
Lapping Valves
NOTE: Exhaust valves that are black in color cannot be
ground and do not require lapping.
Reground or new valves must be lapped in, to provide
fi t. Use a hand valve grinder with suction cup for
fi nal lapping. Lightly coat valve face with fi ne grade
of grinding compound, then rotate valve on seat with
grinder. Continue grinding until smooth surface is
obtained on seat and on valve face. Thoroughly clean
cylinder head in soap and hot water to remove all traces
of grinding compound. After drying cylinder head, apply
a light coating of SAE 10 oil to prevent rusting.
Intake Valve Stem Seal
Always use a new seal when valves are removed
from cylinder head. Seals should also be replaced if
deteriorated or damaged in any way. Never reuse an old
seal.
75
Disassembly/Inspection and Service
32 690 03 Rev. M KohlerEngines.com
Remove Debris Screen, Fan, and Flywheel
NOTE: Always use a fl ywheel strap wrench or fl ywheel
holding tool (see Tools and Aids) to hold fl ywheel
when loosening or tightening fl ywheel and fan
retaining fasteners. Do not use any type of bar
or wedge between fi ns of cooling fan, as fi ns
could become cracked or damaged.
NOTE: Always use a puller to remove fl ywheel from
crankshaft. Do not strike crankshaft or fl ywheel,
as these parts could become cracked or
damaged. Striking puller or crankshaft can
cause crank gear to move, aff ecting crankshaft
endplay.
1. Unsnap debris screen from cooling fan.
2. Remove retaining screw, washer, and fan mounting
plate, securing fan and fl ywheel to crankshaft.
3. Lift cooling fan to disengage 2 drive pins and remove
it from fl ywheel. Two plastic retainers may remain in
fan.
4. Remove fl ywheel from crankshaft by pulling from
under ring gear with large gear puller.
5. Remove fl ywheel key from crankshaft.
Flywheel Inspection
Inspect fl ywheel for cracks, and fl ywheel keyway for
damage. Replace fl ywheel if it is cracked. Replace
fl ywheel, crankshaft, and key if fl ywheel key is sheared
or keyway is damaged.
Inspect ring gear for cracks or damage. Kohler does
not provide ring gears as a serviceable part. Replace
fl ywheel if ring gear is damaged.
Remove Backing Plate and Stator
1. Remove mounting screws and backing plate from
crankcase.
2. Remove screws and stator. Note routing of stator
leads.
Remove Breather Reed Assembly
1. RTV sealant is used between breather reed cover
and crankcase. Remove nut and sealing (fl at)
washer securing breather reed cover to crankcase.
Carefully pry under small tab of cover fl ange to
separate and remove. Do not bend or distort cover.
2. Unscrew and remove mounting stud, retainer and
breather reed.
Crankshaft/Governor Gear/Oil Pump Components
O
N
P
V
T
S
R
K
L
M
H
G
F
A
I
J
Q
U
A
E
D
B
C
A
Governor Cross
Shaft
B Lower Washer
C Nylon Washer D
Push-on Retaining
Ring
E E-Clip F Crankshaft
G Valve Tappets H Camshaft
I Regulating Pin J Shaft
76
Disassembly/Inspection and Service
KohlerEngines.com 32 690 03 Rev. M
Remove Oil Pan Assembly
1. Remove screws securing oil pan to crankcase.
2. Locate splitting tab cast into perimeter of oil pan.
Insert drive end of a 1/2” breaker bar between
splitting tab and crankcase and turn it to break RTV
seal. Do not pry on sealing surfaces as this can
cause leaks.
Inspection
Inspect oil seal in oil pan and remove it if it is worn
or damaged. New oil seal is installed after oil pan is
assembled to crankcase. See Reassembly, Oil Seal in
Oil Pan.
Inspect main bearing surface for wear or damage (refer
to Specifi cations). Replace oil pan assembly if required.
Governor Assembly
Governor gear assembly is located inside oil pan. If
service is required, continue following steps.
Inspection
Inspect governor gear teeth. Replace gear if it is worn,
chipped, or if any teeth are missing. Inspect governor
weights. They should move freely in governor gear.
Disassembly
Governor Shaft Component and Details
C
A
B
A
34.0 mm (1.3386 in.)
33.5 mm (1.3189 in.)
B 19.40 mm (0.7638 in.)
C Gear Shaft
NOTE: Governor gear is held onto shaft by small
molded tabs in gear. When gear is removed from
shaft, these tabs are destroyed and gear must
be replaced. Therefore, remove gear only if
absolutely necessary.
Governor gear must be replaced once it is removed from
oil pan.
1. Use 2 small screwdrivers and carefully pry upward to
remove regulating pin and governor gear assembly.
2. Remove locking tab thrust washer located under
governor assembly.
3. Carefully inspect governor gear shaft and replace it
only if it is damaged. After removing damaged shaft,
press or lightly tap replacement shaft into oil pan to
depth shown.
Reassembly
1. Install locking tab thrust washer on governor gear
shaft with tab down.
2. Position regulating pin within governor gear/
fl yweights assembly and slide both onto governor
shaft until assembly locks into place.
Oil Pump Assembly
Oil pump is mounted inside oil pan. If service is required,
continue with Disassembly, Inspection, and Reassembly.
Disassembly
1. Remove screws.
2. Lift oil pump assembly from oil pan. Remove outer
gerotor gear from oil pan.
3. Ensure ball and spring remain installed in pressure
relief hole of oil pan. If ball and spring fall out of
pressure relief hole, see reassembly for correct
installation.
Inspection
Inspect oil pump housing, gear, and rotors for nicks,
burrs, wear, or any visible damage. If any parts
are worn or damaged, replace oil pump assembly.
Check oil pickup screen for damage or restriction,
replace if necessary. Disassembly of oil pump is not
recommended.
Reassembly
1. Lubricate outer gerotor gear with oil. Install outer
gerotor gear through shaft of oil pump, around inner
gerotor gear. Matching molding dots on inner and
outer gerotor gears is not necessary and will not
aff ect oil pump effi ciency.
2. Reinstall ball, then spring into pressure relief hole of
oil pan.
3. Install oil pump inserting center shaft into
corresponding recess in oil pan. Secure oil pump by
torquing screws (in no specifi c sequence) to 9.9 N·m
(88 in. lb.).
4. After torquing, rotate gear and check for freedom of
movement. Make sure there is no binding. If binding
occurs, loosen screws, reposition pump, retorque
screws and recheck movement.
K Governor Gear L
Locking Tab Thrust
Washer
M Oil Pan N Drain Plug
O Oil Seal P Oil Pump
Q Oil Sentry
™
R Ball
S Spring T Oil Pick-up Screen
U
Ground Strap
Location
V Outer Gerotor Gear
77
Disassembly/Inspection and Service
32 690 03 Rev. M KohlerEngines.com
Remove Camshaft and Valve Tappets
1. Position crankcase so fl ywheel side is down.
Remove camshaft and shim.
2. Remove valve tappets from crankcase and mark
them by their location, as either intake or exhaust
and cylinder 1 or 2. Tappets should always be
reinstalled in same position.
Camshaft Inspection and Service
Check lobes of camshaft for wear or damage. See
Specifi cations for minimum lift specifi cations. Inspect
cam gear for badly worn, chipped or missing teeth.
Replacement of camshaft will be necessary if any of
these conditions exist.
Valve Tappets Inspection
Check base surface of valve tappet(s) for wear or
damage. Replace tappet(s) if condition is questionable
in any way. Corresponding camshaft lobe(s) should also
be checked for wear or damage. Whenever tappets are
replaced, apply a liberal coating of Kohler lubricant to
base of each new tappet before it is installed.
Remove Governor Cross Shaft
Governor Cross Shaft Oil Seal Details
B
A
A 2.0 mm (0.0787 in.) B
Governor Cross
Shaft Seal
1. Round Cross Shaft End: Remove push-on
retaining ring and nylon washer from governor cross
shaft.
7 mm Hex Cross Shaft End: Remove E-Clip and
nylon washer from governor cross shaft.
2. Remove cross shaft with lower washer through
inside of crankcase.
3. Remove governor shaft seal from crankcase.
If governor cross shaft seal is damaged and/or leaks,
replace it using following procedure.
Remove oil seal from crankcase and replace it with a
new one. Apply a light coat of P80 Emulsion Lubricant
(refer to Tools and Aids) to outside diameter of oil seal.
Install new seal to depth shown using a seal installer.
Connecting Rods/Piston/Breather Components
G
I
F
A
B
D
B
E
H
C
A Piston Ring Set B Piston Pin Retainer
C Piston D Piston Pin
E Connecting Rod F
Connecting Rod
End Cap
G Breather Filter H
Breather
Cover
I Oil Seal
Remove Breather Assembly
Breather system is designed to control amount of oil
in head area and still maintain necessary vacuum in
crankcase.
When pistons move downward, crankcase gases are
pushed past reed through breather fi lter into intake
system. Upward travel of pistons closes reed and
creates a low vacuum in lower crankcase. Any oil
separated out through fi lter drains back into crankcase.
1. Remove screws securing breather cover to
crankcase.
2. Carefully remove cover and breather fi lter. Make
sure drain back hole is not plugged or restricted.
Remove Connecting Rods with Pistons and Rings
NOTE: If a carbon ridge is present at top of either
cylinder bore, use a ridge reamer tool to remove
it before attempting to remove piston.
NOTE: Cylinders are numbered on crankcase. Use
numbers to mark each end cap, connecting rod
and piston for reassembly. Do not mix end caps
and connecting rods.
1. Remove screws securing closest connecting rod end
cap. Remove end cap.
2. Carefully remove connecting rod and piston
assembly from cylinder bore.
3. Repeat above procedure for other connecting rod
and piston assembly.
Connecting Rods
Off set, stepped-cap connecting rods are used in all
these engines.
78
Disassembly/Inspection and Service
KohlerEngines.com 32 690 03 Rev. M
Ring failure is usually indicated by excessive oil
consumption and blue exhaust smoke. When rings fail,
oil is allowed to enter combustion chamber where it is
burned along with fuel. High oil consumption can also
occur when piston ring end gap is incorrect because
ring cannot properly conform to cylinder wall under this
condition. Oil control is also lost when ring gaps are not
staggered during installation.
When cylinder temperatures get too high, lacquer and
varnish collect on pistons causing rings to stick, which
results in rapid wear. A worn ring usually takes on a
shiny or bright appearance.
Scratches on rings and pistons are caused by abrasive
material such as carbon, dirt, or pieces of hard metal.
Detonation damage occurs when a portion of fuel charge
ignites spontaneously from heat and pressure shortly
after ignition. This creates 2 fl ame fronts, which meet
and explode to create extreme hammering pressures on
a specifi c area of piston. Detonation generally occurs
from using low octane fuels.
Pre-ignition or ignition of fuel charge before timed spark
can cause damage similar to detonation. Pre-ignition
damage is often more severe than detonation damage.
Pre-ignition is caused by a hot spot in combustion
chamber such as glowing carbon deposits, blocked
cooling fi ns, an improperly seated valve, or wrong spark
plug(s).
Replacement pistons are available in STD bore size,
and 0.25 mm (0.010 in.) oversize. Replacement pistons
include new piston ring sets and new piston pins.
Replacement ring sets are also available separately for
STD, and 0.25 mm (0.010 in.) oversize pistons. Always
use new piston rings when installing pistons. Never use
old rings.
Some important points to remember when servicing
piston rings:
1. Cylinder bore must be de-glazed before service ring
sets are used.
2. If cylinder bore does not need re-boring and if old
piston is within wear limits and free of score or scuff
marks, old piston may be reused.
3. Remove old rings and clean up grooves. Never
reuse old rings.
4. Before installing new rings on piston, place top 2
rings, each in turn, in its running area in cylinder
bore and check end gap. Top compression ring end
gap clearance is 0.189/0.277 mm (0.0074/0.0109 in.)
for a new bore, or 0.531 mm (0.0209 in.) for a used
bore. Middle compression ring end cap is
1.519/1.797 mm (0.0598/0.0708 in.) for a new bore,
or 2.051 mm (0.0808 in.) for a used bore.
5. After installing new compression (top and middle)
rings on piston, make sure top compression ring-to-
groove side clearance and is 0.030/0.070 mm
(0.0010/0.0026 in.) and middle compression ring-to-
groove side clearance 0.030/0.070 mm
(0.0010/0.026 in.). If side clearance is greater than
specifi ed, a new piston must be used.
Inspection and Service
Check bearing area (big end) for excessive wear, score
marks, running and side clearances (See Specifi cations).
Replace rod and cap if scored or excessively worn.
Service replacement connecting rods are available in
STD size and 0.25 mm (0.010 in.) undersize. Undersized
rods, 0.25 mm (0.010 in.), have an identifi cation marking
on lower end of rod shank. Always refer to appropriate
parts information to ensure correct replacements are
used.
Piston and Rings
Inspection
Piston and Rings Components and Details
A
C
B
F
E
D
H
G
A Piston Ring B End Gap
C Identifi cation Mark D Piston
E
Top Compression
Ring
F
Middle Compression
Ring
G Rails H Expander
Scuffi ng and scoring of pistons and cylinder walls occurs
when internal engine temperatures approach welding
point of piston. Temperatures high enough to do this are
created by friction, which is usually attributed to improper
lubrication and/or overheating of engine.
Normally, very little wear takes place in piston boss-
piston pin area. If original piston and connecting rod can
be reused after new rings are installed, original pin can
also be reused but new piston pin retainers are required.
A piston pin is included as part of piston assembly – if
pin boss in piston or pin are worn or damaged, a new
piston assembly is required.
79
Disassembly/Inspection and Service
32 690 03 Rev. M KohlerEngines.com
Install New Piston Rings
NOTE: Rings must be installed correctly. Ring
installation instructions are usually included with
new ring sets. Follow instructions carefully. Use
a piston ring expander to install rings. Install
bottom (oil control) ring fi rst and top
compression ring last.
To install new piston rings, proceed as follows:
1. Oil control ring (bottom groove): Install expander and
then rails. Make sure ends of expander are not
overlapped.
2. Middle compression ring (center groove): Install
center ring using a piston ring expander tool. Make
sure identifi cation mark is up or colored dye stripe (if
contained) is to left of end gap.
3. Top compression ring (top groove): Install top ring
using a piston ring expander tool. Make sure
identifi cation mark is up or colored dye stripe (if
contained) is left of end gap.
Remove Crankshaft
Carefully pull crankshaft from crankcase.
Inspection and Service
Inspect gear teeth of crankshaft. If teeth are badly worn,
chipped, or some are missing, replacement of crankshaft
will be necessary.
Inspect crankshaft bearing surfaces for scoring,
grooving, etc. Measure running clearance between
crankshaft journals and their respective bearing bores.
Use an inside micrometer or telescoping gauge to
measure inside diameter of both bearing bores in vertical
and horizontal planes. Use an outside micrometer to
measure outside diameter of crankshaft main bearing
journals. Subtract journal diameters from their respective
bore diameters to get running clearances. Check results
against values in Specifi cations. If running clearances
are within specifi cation, and there is no evidence of
scoring, grooving, etc., no further reconditioning is
necessary. If bearing surfaces are worn or damaged,
crankcase and/or oil pan will need to be replaced.
Inspect crankshaft keyways. If worn or chipped,
replacement of crankshaft will be necessary.
Inspect crankpin for score marks or metallic pickup.
Slight score marks can be cleaned with crocus cloth
soaked in oil. If wear limits are exceeded, as stated in
Specifi cations, it will be necessary to replace crankshaft.
Remove Flywheel and PTO End Oil Seals
Remove oil seals from crankcase and oil pan.
Crankcase
Inspection and Service
Check all gasket surfaces to make sure they are free of
gasket fragments. Gasket surfaces must also be free of
deep scratches or nicks.
Check cylinder bore for scoring. In severe cases,
unburned fuel can cause scuffi ng and scoring of cylinder
wall. It washes necessary lubricating oils off piston and
cylinder wall. As raw fuel seeps down cylinder wall,
piston rings make metal to metal contact with wall.
Scoring of cylinder wall can also be caused by localized
hot spots resulting from blocked cooling fi ns or from
inadequate or contaminated lubrication.
If cylinder bore is badly scored, excessively worn,
tapered, or out-of-round, resizing is necessary. Use an
inside micrometer to determine amount of wear (refer
to Specifi cations). A 0.25 mm (0.010 in.) oversize piston
is available if resizing is selected. Initially, resize using
a boring bar, then use these following procedures for
honing cylinder.
Honing
Details
A 23°-33° Crosshatch
A
NOTE: Kohler pistons are custom-machined to exacting
tolerances. When over-sizing a cylinder, it
should be machined exactly 0.25 mm (0.010 in.)
over new diameter (refer to Specifi cations).
Oversize Kohler replacement piston will then fi t
correctly.
While most commercially available cylinder hones can
be used with either portable drills or drill presses, use
of a low speed drill press is preferred as it facilitates
more accurate alignment of bore in relation to crankshaft
crossbore. Honing is best accomplished at a drill speed
of about 250 RPM and 60 strokes per minute. After
installing coarse stones in hone, proceed as follows:
1. Lower hone into bore and after centering, adjust so
stones are in contact with cylinder wall. Use of a
commercial cutting-cooling agent is recommended.
2. With lower edge of each stone positioned even with
lowest edge of bore, start drill and honing process.
Move hone up and down while resizing to prevent
formation of cutting ridges. Check size frequently.
80
Disassembly/Inspection and Service
KohlerEngines.com 32 690 03 Rev. M
3. When bore is within 0.064 mm (0.0025 in.) of
desired size, remove coarse stones and replace
them with burnishing stones. Continue with
burnishing stones until bore is within 0.013 mm
(0.0005 in.) of desired size and then use fi nish
stones (220-280 grit) and polish bore to its fi nal size.
A crosshatch should be observed if honing is done
correctly. Crosshatch should intersect at
approximately 23°-33° off horizontal. Too fl at an
angle could cause rings to skip and wear
excessively, and too steep an angle will result in high
oil consumption.
4. After resizing, check bore for roundness, taper, and
size. Use an inside micrometer, telescoping gauge,
or bore gauge to take measurements. These
measurements should be taken at 3 locations in
cylinder – at top, middle, and bottom. Two
measurements should be taken (perpendicular to
each other) at 3 locations.
Clean Cylinder Bore After Honing
Proper cleaning of cylinder walls following boring and/
or honing is very critical to a successful overhaul.
Machining grit left in cylinder bore can destroy an engine
in less than 1 hour of operation after a rebuild.
Final cleaning operation should always be a thorough
scrubbing with a brush and hot, soapy water. Use a
strong detergent capable of breaking down machining
oil while maintaining a good level of suds. If suds break
down during cleaning, discard dirty water and start again
with more hot water and detergent. Following scrubbing,
rinse cylinder with very hot, clear water, dry it completely,
and apply a light coating of engine oil to prevent rusting.
Measuring Piston-to-Bore Clearance
Piston Detail
A
A 6 mm (0.2362 in.)
NOTE: Do not use a feeler gauge to measure piston-to-
bore clearance, it will yield inaccurate
measurements. Always use a micrometer.
Before installing piston into cylinder bore, it is necessary
that clearance be accurately checked. This step is
often overlooked, and if clearances are not within
specifi cations, engine failure will usually result.
Use following procedure to accurately measure piston-
to-bore clearance:
1. Use a micrometer and measure diameter of piston
6 mm (0.2362 in.) above bottom of piston skirt and
perpendicular to piston pin.
2. Use an inside micrometer, telescoping gauge, or
bore gauge and measure cylinder bore.
Measurement approximately 63.5 mm (2.5 in.) below
top of bore and perpendicular to piston pin.
3. Piston-to-bore clearance is diff erence between bore
diameter and piston diameter (step 2 minus step 1).
81
Reassembly
32 690 03 Rev. M KohlerEngines.com
NOTE: Make sure engine is assembled using all
specifi ed torque values, tightening sequences,
and clearances. Failure to observe specifi cations
could cause severe engine wear or damage.
Always use new gaskets.
Make sure all traces of any cleaner are removed before
engine is assembled and placed into operation. Even
small amounts of these cleaners can quickly break down
lubricating properties of engine oil.
Check oil pan, crankcase, cylinder heads, and valve
covers to be certain all old sealing material has been
removed. Use gasket remover, lacquer thinner, or paint
remover to remove any remaining traces. Clean surfaces
with isopropyl alcohol, acetone, lacquer thinner, or
electrical contact cleaner.
Connecting Rods/Piston/Breather Components
G
I
F
A
B
D
B
E
J
H
C
A Piston Ring Set B Piston Pin Retainer
C Piston D Piston Pin
E Connecting Rod F
Connecting Rod
End Cap
G Breather Filter H
Breather
Cover
I Oil Seal J Breather Hose
Install Flywheel End Oil Seal
1. Make sure seal bore of crankcase is clean and free
of any nicks or burrs.
2. Apply a light coat of P80 Emulsion Lubricant (refer to
Tools and Aids) to outside diameter of oil seal.
3. Install oil seal into crankcase using a seal driver.
Make sure oil seal is installed straight and true in
bore and tool bottoms against crankcase.
Install Breather Filter and Breather Cover
Fastener Torque Sequence and Sealant
42
1&5
3
A
A Sealant Bead
NOTE: Always use fresh sealant. Using outdated
sealant can result in leakage. Refer to Tools and
Aids for a listing of approved sealants.
NOTE: To ensure proper adhesion of sealant to both
sealing surfaces, perform step 4 immediately (5
minutes maximum) after application of RTV.
NOTE: RTV sealant should be allowed to cure a
minimum of 1 hour before engine is started.
1. Install breather fi lter between 2 ribs inside breather
chamber.
2. Make sure sealing surfaces are clean and free of
nicks or damage.
3. Apply a 1.5 mm (1/16 in.) bead of RTV sealant to
sealing surface of breather cover. See sealant
pattern.
4. Immediately install cover onto crankcase. Do not
allow RTV sealant to come into contact with any
other components.
5. Secure breather cover with M5 screws. Torque
screws in sequence shown to 6.2 N·m (55 in. lb.)
into a new, cored hole, or 4.0 N·m (35 in. lb.) into a
used hole.
6. Attach breather hose if disconnected earlier.
82
Reassembly
KohlerEngines.com 32 690 03 Rev. M
Crankshaft/Governor Gear/Oil Pump Components
O
N
P
V
T
S
R
K
L
M
H
G
F
A
I
J
Q
U
A
E
D
B
C
A
Governor Cross
Shaft
B Lower Washer
C Nylon Washer D
Push-on Retaining
Ring
E E-Clip F Crankshaft
G Valve Tappets H Camshaft
I Regulating Pin J Shaft
K Governor Gear L
Locking Tab Thrust
Washer
M Oil Pan N Drain Plug
O Oil Seal P Oil Pump
Q Oil Sentry
™
R Ball
S Spring T Oil Pick-up Screen
U
Ground Strap
Location
V Outer Gerotor Gear
Install Governor Cross Shaft
1. Lubricate governor cross shaft bearing surfaces in
crankcase with engine oil.
2. Slide lower washer onto governor cross shaft and
install cross shaft from inside of crankcase.
3. Round Cross Shaft End: Install nylon washer onto
governor cross shaft, then start push-on retaining
ring. Hold cross shaft up in position, place a 0.50
mm (0.020 in.) feeler gauge on top of nylon washer,
and push retaining ring down shaft to secure.
Remove feeler gauge, which will have established
proper end play.
7 mm Hex Cross Shaft End: Install nylon washer
onto governor cross shaft. Install E-clip into groove
on cross shaft. Use a 0.25 mm (0.010 in.) feeler
gauge to make sure gap between washer and clip is
at least 0.25 mm (0.010 in.).
Install Crankshaft
1. Lubricate fl ywheel side main bearing surface and
lips of oil seal in crankcase with clean engine oil.
2. Carefully slide fl ywheel end of crankshaft through
main bearing in crankcase.
83
Reassembly
32 690 03 Rev. M KohlerEngines.com
Install Connecting Rods with Pistons and Rings
Piston and Connecting Rod Details
A
B
A Side 1 B Side 2
Connecting Rod Screw Details
A
B
Type Torque
A Black Coating 11.3 N·m (100 in. lb.)
B
Gray Metallic
Coating
13.6 N·m (120 in. lb.)
NOTE: Cylinders are numbered on crankcase. Make
sure to install piston, connecting rod, and end
cap into its appropriate cylinder bore as
previously marked during disassembly. Do not
mix end caps and connecting rods.
NOTE: Proper orientation of piston/connecting rod
assemblies inside engine is extremely important.
Improper orientation can cause extensive wear
or damage. Be certain pistons and connecting
rods are assembled exactly as shown.
NOTE: Align chamfer of connecting rod with chamfer of
its mating end cap. When installed, fl at faces of
connecting rods should face each other. Faces
with raised rib should be toward outside.
1. Stagger piston rings in grooves until end gaps are
120° apart. Oil ring rails should also be staggered.
2. Lubricate cylinder bore, piston, and piston rings with
engine oil. Compress rings using a piston ring
compressor.
3. Lubricate crankshaft journals and connecting rod
bearing surfaces with engine oil.
4. Make sure FLY stamping on piston is facing toward
fl ywheel side of engine. Use a hammer with a rubber
or wood grip and gently tap piston into cylinder. Be
careful oil ring rails do not spring free between
bottom of ring compressor and top of cylinder.
5. Install inner rod cap to connecting rod using screws.
Two diff erent types of coatings on connecting rod
screws have been used. If black coating, torque in
increments to 11.3 N·m (100 in. lb.). If gray metallic
coating, it is not necessary to lubricate this screw,
torque in increments to 13.6 N·m (120 in. lb.).
Illustrated instructions are provided in service rod
package.
6. Repeat above procedure for other connecting rod
and piston assembly.
Install Valve Tappets and Camshaft
NOTE: Exhaust valve tappets are located on output
shaft side of engine, while intake valve tappets
are located on fan side of engine. Cylinder
number is embossed on outside of each cylinder
on crankcase. Valve tappets should always be
installed in same position as before disassembly.
1. Apply camshaft lubricant to contact surface of valve
tappets. Note mark or tag identifying tappets and
install them in their appropriate crankcase locations.
A small amount of grease applied to stems will hold
valve tappets up until camshaft is installed.
2. Liberally apply camshaft lubricant to lobes of
camshaft. Lubricate camshaft bearing surfaces of
crankcase and camshaft with engine oil.
3. Position timing mark of crankshaft gear at 12 o’clock
position.
4. Turn governor cross shaft clockwise until lower end
(blade) is laying against bottom of cylinder. Make
sure cross shaft remains in this position while
installing camshaft.
5. Slide camshaft into bearing surface of crankcase,
positioning timing mark of camshaft gear at 6 o’clock
position. Make sure camshaft gear and crankshaft
gear mesh with both timing marks aligned.
Oil Pump Assembly
Oil pump is mounted inside oil pan. If service
was required and oil pump was removed, refer to
Disassembly/Inspection and Service procedure.
Governor Assembly
Governor assembly is located inside oil pan. If service
was required and governor was removed, refer to
Disassembly/Inspection and Service procedure.
84
Reassembly
KohlerEngines.com 32 690 03 Rev. M
Install Oil Seal in Oil Pan
Oil Seal Component and Detail
A
B
A 6.5 mm (0.255 in.) B Oil Seal
1. Check to make sure there are no nicks or burrs in
crankshaft bore of oil pan.
2. Apply a light coat of P80 Emulsion Lubricant (refer to
Tools and Aids) to outside diameter of oil seal.
3. Drive oil seal into oil pan using a seal driver. Make
sure oil seal is installed straight and true in bore, to
depth shown.
Install Oil Pan Assembly
Sealant Pattern
Fastener Torque Sequence
1
10
8
6
4
2
9
7
5
3
RTV sealant is used as a gasket between oil pan
and crankcase. Refer to Tools and Aids for a listing of
approved sealants. Always use fresh sealant. Using
outdated sealant can result in leakage.
1. Be sure sealing surfaces have been cleaned and
prepared as described at beginning of Reassembly.
2. Check to make sure there are no nicks or burrs on
sealing surfaces of oil pan or crankcase.
3. Apply a 1.5 mm (1/16 in.) bead of black RTV sealant
to sealing surface of oil pan. See sealant pattern. Oil
pan must be installed within 5 minutes of sealant
being applied for proper sealing to occur.
4. Make sure end of governor cross shaft is lying
against bottom of cylinder inside crankcase.
5. Install oil pan to crankcase. Carefully seat camshaft
with shim and crankshaft into their mating bearings.
Rotate crankshaft to help engage oil pump and
governor gear meshes.
6. Install 10 screws securing oil pan to crankcase.
Torque fasteners in sequence shown to 24.4 N·m
(216 in. lb.).
85
Reassembly
32 690 03 Rev. M KohlerEngines.com
Install Breather Reed and Breather Reed Cover
Breather Reed Cover Sealant
A
A Sealant Bead
NOTE: RTV sealant should be allowed to cure a
minimum of 1 hour before engine is started.
1. Install breather reed, followed by retainer over
passage hole and mounting hole in crankcase. Hold
in position and secure with mounting stud. Torque
stud to 6.2 N·m (55 in. lb.) into a new, cored hole, or
4.0 N·m (35 in. lb.) into a used hole.
2. Invert breather reed cover and apply a 1.5 mm
(1/16 in.) bead of RTV sealant to perimeter fl ange of
cover as shown. Use Loctite
®
5900
TM
or 5910
TM
.
3. Immediately install breather reed cover over
mounting stud and onto crankcase. Do not allow
RTV sealant to come in contact with breather reed,
or reed sealing surface.
4. Secure with a new sealing washer and M5 nut.
Torque nut to 1.3 N·m (12 in. lb.). Check that a
complete seal has occurred by RTV sealant being
squeezed out around entire fl ange perimeter.
Install Stator and Backing Plate
1. Apply pipe sealant with Tefl on
®
(Loctite
®
PST
®
592
TM
or equivalent) to stator mounting holes.
2. Position stator aligning mounting holes so leads are
at bottom, toward crankcase.
3. Install and torque screws to 8.8 N·m (78 in. lb.).
4. Install backing plate. Secure with screws. Torque
screws in a crisscross pattern to 7.3 N·m (65 in. lb.).
Install Flywheel and Fan
CAUTION
Damaging Crankshaft and Flywheel can
cause personal injury.
Using improper procedures can lead to broken
fragments. Broken fragments could be thrown from
engine. Always observe and use precautions and
procedures when installing fl ywheel.
Flywheel/Ignition/Breather Components
I
K
L
J
M
F
G
H
C
B
A
D
E
A Flywheel Screw B Fan
C Washer D Fan Mounting Plate
E Magnet F Flywheel
G Stator H Backing Plate
I Breather Reed Cover J Stud
K Retainer L Breather Reed
M Flywheel Key
86
Reassembly
KohlerEngines.com 32 690 03 Rev. M
NOTE: Before installing fl ywheel, make sure crankshaft taper and fl ywheel hub are clean, dry, and completely free of
lubricants. Presence of lubricants can cause fl ywheel to be overstressed and damaged when screw is torqued
to specifi cations.
NOTE: Make sure fl ywheel key is installed properly in keyway. Flywheel can become cracked or damaged if key is
not installed properly.
1. Install fl ywheel key into keyway of crankshaft. Make sure key is properly seated and parallel with shaft taper.
2. Install fl ywheel onto crankshaft being careful not to shift fl ywheel key.
3. Install fan onto fl ywheel, so locating pins fi t into corresponding recesses. Drive 2 retainers down completely.
4. Install fan mounting plate onto fan, aligning 4 cutouts, followed by heavy fl at washer and screw.
5. Use a fl ywheel strap wrench or holding tool to hold fl ywheel. Torque screw securing fl ywheel to crankshaft to 74.5
N·m (55 ft. lb.).
Cylinder Head Components
A
B
C
I
E
F
G
H
D
K
L
M
N
J
P
O
M
R
Q
N
S
#2#1
4 2
1
3
2 4
3
1
A Gasket B Valve C Cylinder Head D Valve Spring Cap
E Valve Stem Seal F Valve Spring G Valve Spring Keeper H Stud
I Spark Plug J Guide Plate K Push Rod L Rocker Arm
M Rocker Arm Pivots N Adjusters O Washer P
Stamped Steel Valve
Cover (RTV)
Q
Plastic Valve Cover
(O-Ring)
R O-Ring S Torque Sequence
87
Reassembly
32 690 03 Rev. M KohlerEngines.com
Adjust Valve Clearance
Adjusters Retaining Push Rods
A
B
A Adjuster B Rocker Arm
1. Rotate crankshaft to establish TDC on compression
stroke for cylinder 1.
Check for:
a. Compression will be felt through spark plug hole.
b. Keyway of crankshaft will be aligned with cylinder
1.
c. No rocker arm/push rod movement if crankshaft
is rotated slightly back and forth. If they are
moving, rotate crankshaft 1 full revolution.
2. Insert a 0.127 mm (0.005 in.) feeler gauge between
end of 1 valve and rocker arm. Turn adjuster until a
slight drag is felt. Hold in this position and tighten
setscrew securely. Torque setscrew to 7.9 N·m
(70 in. lb.). After tightening recheck adjustment.
Proper valve clearance is 0.101/0.152 mm
(0.004/0.006 in.).
3. Repeat procedure for other valve on side 1.
4. Viewed from PTO end, rotate crankshaft 270° (3/4
turn) counterclockwise and align crankshaft keyway
with cylinder 2, which now puts cylinder at TDC on
compression stroke.
5. Repeat steps 3-4 for setting valve clearance on side
2.
6. Rotate crankshaft to check for free operation of
valve train. Check for clearance between valve
spring coils at full lift, or bending of push rod(s) can
occur. Minimum allowable clearance is 0.25 mm
(0.010 in.).
Check Assembly
Rotate crankshaft a minimum of 2 revolutions to check
longblock assembly and overall proper operation.
Assemble and Install Cylinder Heads
Valve Stem Seals
Use a new seal whenever valve is removed, or if seal is
deteriorated or damaged. Never reuse an old seal.
Assemble Cylinder Heads
Prior to installation, lubricate all components with engine
oil, paying particular attention to lip of valve stem seal,
valve stems, and valve guides. Install following items in
order listed below using a valve spring compressor.
● Intake and exhaust valves.
● Valve stem seal.
● Washer (intake valve only).
● Valve springs.
● Valve spring caps.
● Valve spring keepers.
Install Cylinder Heads
NOTE: Match numbers embossed on cylinder heads
and crankcase.
NOTE: Push rods should always be installed in same
position as before disassembly.
1. Check to make sure there are no nicks or burrs on
sealing surfaces of cylinder head or crankcase.
Make sure dowel locating pins are in lower 2 cylinder
bolt holes on each side.
2. Install a new cylinder head gasket (with printing up)
on each side.
3. Install each cylinder head and start 4 screws.
4. Torque screws in 2 stages; fi rst to 22.6 N·m
(200 in. lb.), then fi nally to 41.8 N·m (370 in. lb.),
following sequence.
Install Rocker Arms
1. Note mark or tag identifying push rod as either
intake or exhaust and cylinder 1 or 2. Check each
push rod is straight and not bent. Dip ends of push
rods in engine oil and install in their original
positions, making sure each push rod ball seats in its
tappet socket.
2. Install guide plate and studs. Torque studs to
11.3 N·m (100 in. lb.).
3. Apply grease to contact surfaces of adjusters, rocker
arms and rocker arm pivots. Install rocker arms and
rocker arm pivots onto appropriate cylinder head,
and install adjuster fi nger tight. Make sure set screw
is backed out until fl ush with adjuster.
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Reassembly
KohlerEngines.com 32 690 03 Rev. M
Install Valve Covers
Plastic valve covers contain integral bolt hole spacers
molded in place. Sealing of plastic valve covers is
accomplished using a yellow colored O-ring. In stamped
steel valve covers sealing is accomplished using RTV
sealant.
Plastic Valve Covers
Plastic Valve Cover Torque Sequence
1&5
3
2
4
1. Make sure sealing surfaces of valve covers and
cylinder heads are clean and free of any nicks or
burrs.
2. Install a new O-ring in groove of each cover. Do Not
use gaskets or RTV sealant.
3. Position covers on cylinder heads. If a pulse style
fuel pump is used, valve cover with pulse fitting hole
must be installed on side 2. Install screws in each
cover and finger tighten.
4. Using sequence shown, torque valve cover screws
to the appropriate torque for style of screw.
Hex Flange to 9.0 N·m (80 in. lb.)
Pan Head to 6.2 N·m (55 in. lb.)
Stamped Steel Valve Covers
Stamped Steel Valve Cover RTV Sealant
A
A RTV Sealant
Stamped Steel Valve Cover Torque Sequence
1&5 3
2
4
NOTE: Always use fresh sealant. Using outdated
sealant can result in leakage. Refer to Tools and
Aids for information on sealant dispenser.
NOTE: To ensure proper adhesion of sealant to both
sealing surfaces, perform step 3 immediately (5
minutes maximum) after application of RTV.
RTV silicone sealant is used as a gasket between valve
cover and cylinder head. Refer to Tools and Aids for a
listing of approved sealants.
1. Prepare sealing surfaces of cylinder heads and
valve covers. Flatness of sealing surface must be
checked prior to reinstallation. See Disassembly.
2. Apply a 1.5 mm (1/16 in.) bead of sealant to valve
cover as shown.
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3. Position covers on cylinder heads. If a pulse style fuel pump is used valve cover with pulse fi tting hole must be
installed on side 2. Install screws in each cover and fi nger tighten.
4. Torque valve cover fasteners to 13.6 N·m (120 in. lb.), using sequence shown.
Install Spark Plugs
1. Check gap using wire feeler gauge. Adjust gap to 0.76 mm (0.030 in.).
2. Install plug into cylinder head.
3. Torque plug to 27 N·m (20 ft. lb.).
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Reassembly
KohlerEngines.com 32 690 03 Rev. M
External Engine Components
J
T
E
L
G
S
R
E
E
F
H
H
I
V
U
K
B
A
C
D
M
O
N
P
Q
W
R
S
B
S
B
A Fixed Guard B Air Cleaner Cover C Debris Screen D Blower Housing
E Hose Clamp F Fuel Pump G Hose Clip H Fuel Line
I Fuel Filter J Oil Filter K Outer Baffl e L Electric Starter
M Inner Baffl e N Ignition Module O Intake Manifold P Carburetor
Q Gasket R Air Cleaner Base S Air Cleaner Element T Rectifi er-Regulator
U Dipstick Tube V Oil Fill/Dipstick W Breather Hose
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32 690 03 Rev. M KohlerEngines.com
Install Ignition Modules
Smart-Choke
™
Defl ector Support Tab (if equipped)
A
B
A Position tab towards crankcase.
B Rotate tab against module before tightening.
NOTE: On some early production engines equipped
with Smart-Choke
™
, make sure to install
defl ector support tab on #2 cylinder ignition
module.
1. Rotate fl ywheel to position magnet away from
ignition module bosses.
2. CDI modules are installed on cylinder 1 with single
kill tab away from cylinder/towards you, and on
cylinder 2 with single kill tab towards cylinder/away
from you.
MDI modules are installed with fl at side out/towards
you.
3. Install each ignition module to crankcase bosses.
Slide modules up as far away from fl ywheel as
possible and snug screws to hold them in position.
4. Rotate fl ywheel to position magnet directly under 1
ignition module.
5. Insert a 0.25 mm (0.009 in.) fl at feeler gauge
between magnet and ignition module. Loosen
screws enough to allow magnet to pull module down
against feeler gauge.
6. Torque screws to 4.0-6.2 N·m (35-55 in. lb.).
7. Repeat steps 4 through 6 for other ignition module.
8. Rotate fl ywheel back and forth checking for
clearance between magnet and ignition modules.
Make sure magnet does not strike modules. Check
gap with a feeler gauge and readjust if necessary.
Final air gap 0.203/0.305 mm (0.008/0.012 in.).
Install Intake Manifold
Torque Sequence
1
2
3
4
1. On engines equipped with Smart-Choke
™
, install air
vane defl ector into intake manifold. Torque screw to
1 N·m (9 in. lb.).
2. Install intake manifold using new O-rings, with wiring
harness attached, onto cylinder heads. Slide any
wiring harness clips onto appropriate bolts before
installing. Using sequence shown, torque screws in
2 increments, fi rst to 7.4 N·m (66 in. lb.), then to
9.9 N·m (88 in. lb.).
3. Connect kill lead to tab terminal on standard ignition
modules.
Install Rectifi er-Regulator (if equipped)
1. Install B+ terminal/lead into center position of
rectifi er-regulator plug so it locks in place, and
connect plug to rectifi er-regulator.
2. Attach rectifi er-regulator to opening in backing plate
from underside, and secure with mounting screws.
Torque screws to 4.0 N·m (35 in. lb.).
Install Inner and Outer Cylinder Baffl es
1. Attach outer cylinder baffl es and secure with M6
screw (lower cylinder location), and M5 screw into
backing plate. Tighten screws as listed following step
2.
2. Attach inner baffl es including any lifting straps to
cylinder head fl anges and to 2 crankcase mounting
bosses. Lift strap should be outside outer baffl e.
Secure with M5 screws. Remaining lower inner
baffl e mounting screws will be installed later.
Torque baffl e mounting screws:
M5 screws: 6.2 N·m (55 in. lb.) into a new cored
hole, or 4.0 N·m (35 in. lb.) into a used hole.
M6 screws: 10.7 N·m (95 in. lb.) into a new cored
hole, or 7.3 N·m (65 in. lb.) into a used hole.
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Install Carburetor
WARNING
Explosive Fuel can cause fi res and severe
burns.
Do not fi ll fuel tank while engine is hot or
running.
Gasoline is extremely fl ammable and its vapors can
explode if ignited. Store gasoline only in approved
containers, in well ventilated, unoccupied buildings,
away from sparks or fl ames. Spilled fuel could ignite
if it comes in contact with hot parts or sparks from
ignition. Never use gasoline as a cleaning agent.
1. Install a new carburetor gasket. Make sure all holes
align and are open.
2. Install carburetor, throttle linkage and governor lever
as an assembly.
3. If carburetor is equipped with a fuel solenoid,
connect red (power) lead. Attach eyelet terminal of
ground lead to inner top carburetor cover mounting
screw.
Install Carburetor with Smart-Choke
™
Smart-Choke
™
Carburetor Components
E
C
G
B
F
A
A Air Cleaner Base B Breather Hose
C Ground Lead D Solenoid Lead
E
Smart-Choke
™
Bracket Assembly
F Thermostat
G Carburetor
Choke Unloader Linkage
A
B
A
Choke Unloader
Linkage
B
Choke
Lever
Actuator Lever Engaged with Choke Shaft Pin
A
B
A Actuator Lever B Choke Shaft Pin
NOTE: If thermostat was removed from assembly, refer
to procedure in Fuel System section to install.
1. Install new carburetor gasket. Make sure all holes
align and are open.
2. Install carburetor, throttle linkage and governor lever
as an assembly.
3. Connect choke unloader linkage from air vane
defl ector to carburetor.
4. If carburetor is equipped with a fuel solenoid,
connect red (power) lead. Attach eyelet terminal of
ground lead to inner top carburetor cover mounting
screw.
5. Install a new air cleaner base gasket and air cleaner
base onto mounting studs. Install Smart-Choke
™
bracket assembly. Ensure actuator lever is engaged
with pin on choke shaft. Torque nuts to 6.2-7.3 N·m
(55-65 in. lb.)
6. Connect breather hose to air cleaner base and
secure with clamp.
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Install Carburetor with eChoke
™
eChoke
™
Carburetor Components
A
D
B
C
E
F
A Air Cleaner Base B Solenoid Lead
C Stepper Motor D
eChoke
™
Bracket
Assembly
E Carburetor F Nuts
NOTE: On engines equipped with eChoke
™,
stepper
motor has a special retract routine that can be
activated to ensure motor is in correct position
prior to removal or upon replacement of stepper
motor when a problem is shown to exist with
stepper motor assembly and carburetor.
Activation of this routine will occur by initiating
three (3) consecutive Key On–Off cycles. Every
Key On and Off should be > 2 seconds and <
3.5 seconds. Note that if no other connections
are disturbed, stepper motor will be repositioned
at next key ON and master module will go back
to normal choke operation mode.
1. Install a new carburetor gasket. Make sure all holes
align and are open.
2. Install carburetor, throttle linkage and governor lever
as an assembly.
3. If carburetor is equipped with a fuel solenoid,
connect red (power) lead. Attach eyelet terminal of
ground lead to inner top carburetor cover mounting
screw.
4. Install a new air cleaner base gasket and air cleaner
base onto mounting studs. Install eChoke
™
bracket
assembly. Connect eChoke
™
stepper motor harness
and follow routine indicated in NOTE in this section
prior to setting link.
5. Connect choke linkage to choke actuator lever on
main control bracket assembly. Torque nuts to
6.2-7.3 N·m (55-65 in. lb.).
6. Connect breather hose to air cleaner base and
secure with clamp.
Install External Governor Controls
Control Bracket Components
F
G
C
C
C
B
A
D
D
E
A Choke Linkage B Throttle Linkage
C Governor Lever D Governor Spring
E Cross Shaft F Control Bracket
G Dampener Spring
Throttle and Choke Components
A
K
B
D
E
F
G
C
I
J
H
A Screw B Choke Lever
C Throttle Lever D
Throttle Actuator
Lever
E Control Bracket F Choke Return Spring
G Lock Nut M5x0.8 H Shoulder Washer
I Flat Washer J Nylon Washer
K Wave Washer
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1. Install governor lever onto governor cross shaft if
disconnected previously.
2. Make sure throttle linkage is connected to governor
lever and throttle lever on carburetor. Connect choke
linkage to carburetor choke lever.
3. Attach fuel line to carburetor and secure with a
clamp.
4. Install a new air cleaner base gasket and air cleaner
base onto mounting studs. Torque nuts to
6.2-7.3 N·m (55-65 in. lb.).
5. Connect breather hose to air cleaner base and
secure with clamp.
6. Move governor lever toward carburetor as far as it
will go (wide-open throttle), and hold in position.
7. Round Cross Shaft End: Insert a nail or similar
tool into hole on cross shaft and rotate shaft
counterclockwise as far as will turn, then torque nut
to 6.8 N·m (60 in. lb.).
7 mm Hex Cross Shaft End: Use 7 mm hex socket
on end of cross shaft and rotate shaft
counterclockwise (viewed from end) as far as it will
turn, then torque nut to 6.8 N·m (60 in. lb.).
Install Air Cleaner Element
Install air cleaner element (with precleaner if equipped),
onto air cleaner base.
Install Throttle and Choke Controls
Governor Lever Hole Position
A
E
D
C
B
A Governor Lever B Hole 1
C Hole 2 D Hole 3
E Hole 4
1. Connect choke linkage to choke actuator lever on
main control bracket assembly.
2. Install main control bracket to cylinder heads using
screws. Two lower screws should also secure inner
baffl es. Torque screws to 10.7 N·m (95 in. lb.) into
new holes, or 7.3 N·m (65 in. lb.) into used holes.
3. Connect governed idle spring to governor lever and
main control bracket. Connect governor spring from
throttle control bracket to appropriate hole in
governor lever.
Install Electric Starter Motor
1. Install starter motor and lift bracket.
2. Torque screws to 23.8 N·m (211 in. lb.).
3. On models with a solenoid shift starter, connect
leads to solenoid.
Install Debris Screen
Snap screen onto fan.
Install Blower Housing
NOTE: Do not completely tighten screws until all are
installed to allow shifting for hole alignment.
1. Install blower housing onto engine. Start all
mounting screws. Make sure wire harness and spark
plug leads exit out through appropriate openings in
shrouding. Attach any fuel line clamps used.
2. Torque screws as follows:
M5 Blower Housing Screws: 6.2 N·m (55 in. lb.) in a
new hole, or 4.0 N·m (35 in. lb.) in a used hole.
M4 HI-LO Screws: 2.8 N·m (25 in. lb.).
M3 HI-LO Screws: 2.3 N·m (20 in. lb.).
3. Install and secure air cleaner cover.
Install Fixed Guard (if equipped)
Install fi xed guard. Securely tighten screw (if equipped).
Install Dipstick Tube
1. Lubricate dipstick tube O-ring and install into
crankcase.
2. Secure to backing plate using M5 screw.
3. Torque screw to 4.0 N·m (35 in. lb.).
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32 690 03 Rev. M KohlerEngines.com
Install Fuel Pump
WARNING
Explosive Fuel can cause fi res and severe
burns.
Do not fi ll fuel tank while engine is hot or
running.
Gasoline is extremely fl ammable and its vapors can
explode if ignited. Store gasoline only in approved
containers, in well ventilated, unoccupied buildings,
away from sparks or fl ames. Spilled fuel could ignite
if it comes in contact with hot parts or sparks from
ignition. Never use gasoline as a cleaning agent.
Fuel Pump Components
A
F
B
C
D
E
A Outlet Fuel Line B Pulse Hose
C Inlet Fuel Line D Fuel Line Clamp
E Fuel Filter F Fuel Pump
NOTE: If a new fuel pump is being installed, make sure
orientation of new pump is consistent with
removed pump. Internal damage may occur if
installed incorrectly.
1. Connect pulse hose to valve cover. Valve cover
should be situated between 2 formed lips on pulse
hose.
2. Attach pulse hose to fuel pump and secure with a
clamp. Mount fuel pump to blower housing with
screws. Torque screws to 2.8 N·m (25 in. lb.).
3. Connect inlet and outlet fuel lines to pump. Route
inlet fuel line through fuel line clamp (if used) as
shown.
Install Muffl er
1. Install muffl er and attaching hardware to muffl er
bracket. Torque screws to 9.9 N·m (88 in. lb.).
2. Install M8 nuts or 5/16-18 head capscrews (based
on head design), to secure muffl er. Torque hex nuts
to 24.4 N·m (216 in. lb.), lock nuts to 27.8 N·m (246
in. lb.), or capscrews to 16.9 N·m (150 in. lb.).
Install Oil Filter and Fill Crankcase with Oil
NOTE: Make sure oil drain plug is installed and torqued
to specifi cation to prevent oil leakage.
1. Install oil drain plug. Torque plug to 13.6 N·m
(10 ft. lb.).
2. Place new fi lter in shallow pan with open end up. Fill
with new oil until oil reaches bottom of threads. Allow
2 minutes for oil to be absorbed by fi lter material.
3. Apply a thin fi lm of clean oil to rubber gasket on new
fi lter.
4. Refer to instructions on oil fi lter for proper
installation.
5. Fill crankcase with new oil. Level should be at top of
indicator on dipstick.
6. Reinstall oil fi ll/dipstick and tighten securely.
Connect Spark Plug Leads
Connect leads to spark plugs.
Prepare Engine for Operation
Engine is now completely reassembled. Before starting
or operating engine, be sure to do following.
1. Make sure all hardware is tightened securely.
2. Make sure oil drain plug, Oil Sentry
TM
pressure
switch, and a new oil fi lter are installed.
3. Adjust carburetor idle speed adjusting screw as
necessary.
Testing Engine
It is recommended engine be operated on a stand or
bench prior to installation in piece of equipment.
1. Run engine at idle for 2-3 minutes, then 5-6 minutes
more between idle and midrange.
2. Adjust idle speed screw and high-speed stop as
necessary. Make sure maximum engine speed does
not exceed 3750 RPM (no load).
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