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Kohler Command CH620 Service Manual
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Kohler Command CH620 Service Manual

Kohler Command CH620 Service Manual

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CH18-CH25, CH620-CH730, CH740, CH750
Service Manual
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.
2
Safety
3
Maintenance
5
Specifi cations
15
Tools and Aids
18
Troubleshooting
23
Air Cleaner/Intake
24
Fuel System
37
Governor System
55
Lubrication System
57
Electrical System
76
Starter System
85
Clutch
87
Disassembly/Inspection and Service
102
Reassembly
24 690 06 Rev. O
KohlerEngines.com
1

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Summary of Contents for Kohler Command CH620

  • Page 1 CH18-CH25, CH620-CH730, CH740, CH750 Service Manual 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. Safety Maintenance Specifi...
  • Page 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. CAUTION WARNING WARNING...
  • Page 3 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). 24 690 06 Rev. O...
  • Page 4 KOHLER PRO Extended Life Oil Filter. Alternative full-synthetic oil). Remove spark plug(s) and pour engine oils and oil fi lters may be used with KOHLER about 1 oz. of engine oil into cylinder(s). Replace engines but require 100-Hour oil and 200-Hour oil fi lter spark plug(s) and crank engine slowly to distribute change intervals for proper maintenance.
  • Page 5 Specifi cations Engine Dimensions with Low-Profi le Air Cleaner Dimensions in millimeters. Inch equivalents shown in [ ]. 24 690 06 Rev. O KohlerEngines.com...
  • Page 6 Specifi cations Engine Dimensions with Heavy-Duty Air Cleaner Dimensions in millimeters. Inch equivalents shown in [ ]. 135.00 424.61 130.00 285.90 304.48 [5.315] [16.717] [5.118] [11.256] [11.987] 50.85 AIR FILTER RAIN 272.17 AIR FILTER COVER 93.33 [2.002] CAP REMOVAL ASSEMBLY REMOVAL [3.674] [10.715] 414.17...
  • Page 7 Lubricate threads with engine oil prior to assembly. 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.
  • Page 8 Specifi cations CH18/CH20/ CH22/CH23/ CH22/ CH620 CH25/ CH620/CH621/ CH640 CH730/ TORQUE SPECIFICATIONS CH640/CH641 CH670/CH680 CH740 CH750 Closure Plate Fastener 24.4 N·m (216 in. lb.) Connecting Rod Cap Fastener (torque in increments) 8 mm straight shank 22.7 N·m (200 in. lb.) 8 mm step-down 14.7 N·m (130 in.
  • Page 9 Specifi cations CH18/CH20/ CH22/CH23/ CH22/ CH620 CH25/ CH620/CH621/ CH640 CH730/ TORQUE SPECIFICATIONS CH640/CH641 CH670/CH680 CH740 CH750 Solenoid (Starter) Mounting Hardware Nippondenso Starter 6.0-9.0 N·m (53-79 in. lb.) Delco-Remy Starter 4.0-6.0 N·m (35-53 in. lb.) Nut, Positive (+) Brush Lead Nippondenso Starter 8.0-12.0 N·m (71-106 in.
  • Page 10 Specifi cations CH18/CH20/ CH22/CH23/ CH22/ CH620 CH25/ CH620/CH621/ CH640 CH730/ CLEARANCE SPECIFICATIONS CH640/CH641 CH670/CH680 CH740 CH750 Connecting Rod Connecting Rod-to-Crankpin Running Clearance 0.030/0.055 mm (0.0012/0.0022 in.) Max. Wear Limit 0.070 mm (0.0028 in.) Connecting Rod-to-Crankpin Side Clearance 0.26/0.63 mm (0.0102/0.0248 in.) Connecting Rod-to-Piston Pin Running Clearance 0.015/0.028 mm (0.0006/0.0011 in.) Piston Pin End I.D.
  • Page 11 Specifi cations CH18/CH20/ CH22/CH23/ CH22/ CH620 CH25/ CH620/CH621/ CH640 CH730/ CLEARANCE SPECIFICATIONS CH640/CH641 CH670/CH680 CH740 CH750 Cylinder Bore Bore I.D. 77.000/ 80.000/ 82.988/83.013 mm 77.025 mm 80.025 mm (3.2672/3.2682 in.) (3.0315/ (3.1496/ 3.0325 in.) 3.1506 in.) Max. Wear Limit 77.063 mm 80.065 mm 83.051 mm (3.0340 in.)
  • Page 12 Specifi cations CH18/CH20/ CH22/CH23/ CH22/ CH620 CH25/ CH620/CH621/ CH640 CH730/ CLEARANCE SPECIFICATIONS CH640/CH641 CH670/CH680 CH740 CH750 Piston, Piston Rings, and Piston Pin (Style A continued) Middle Compression Ring-to-Groove Side Clearance 0.040/ 0.030/ 0.015/0.037 mm 0.080 mm 0.076 mm (0.0006/0.0015 in.) (0.0016/ (0.0012/ 0.0031 in.)
  • Page 13 Specifi cations CH18/CH20/ CH22/CH23/ CH22/ CH620 CH25/ CH620/CH621/ CH640 CH730/ CLEARANCE SPECIFICATIONS CH640/CH641 CH670/CH680 CH740 CH750 Piston, Piston Rings, and Piston Pin (Style B continued) Middle Compression Ring End Gap New Bore 1.400/ 1.519/1.797 mm 1.679 mm (0.0598/0.0708 in.) (0.0551/ 0.0661 in.) Used Bore (Max) 1.941 mm...
  • Page 14 Specifi cations GENERAL TORQUE VALUES 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)
  • Page 15 Shrader Valve Adapter Hose DTI-037 Wire Probe Set (2 pieces regular wire with clip; 1 piece fused wire) DTI-031 Hose Removal Tool, Dual Size/End (also sold as individual Kohler tool) DTI-033 K-Line Adapter Jumper Lead Wiring Harness Kohler 25 176 23-S...
  • Page 16 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. Reamer Handle Design Technology Inc. For hand reaming using Kohler 25 455 12-S reamer. DTI-K830 AIDS Description Source/Part No.
  • Page 17 Tools and Aids FLYWHEEL HOLDING TOOL ROCKER ARM/CRANKSHAFT TOOL A fl ywheel holding tool can be made out of an old junk A spanner wrench to lift rocker arms or turn crankshaft fl ywheel ring gear and used in place of a strap wrench. may be made out of an old junk connecting rod.
  • Page 18 Troubleshooting 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.
  • Page 19 Troubleshooting EXTERNAL ENGINE INSPECTION Engine Loses Power NOTE: It is good practice to drain oil at a location away ● Dirty air cleaner element. from workbench. Be sure to allow ample time for ● Engine overheated. complete drainage. ● Excessive engine load. ●...
  • Page 20 Troubleshooting CRANKCASE VACUUM TEST WARNING WARNING Carbon Monoxide can cause severe nausea, Rotating Parts can cause severe injury. fainting or death. Stay away while engine is in operation. Avoid inhaling exhaust fumes. Never run engine indoors or in enclosed spaces. Keep hands, feet, hair, and clothing away from all Engine exhaust gases contain poisonous carbon moving parts to prevent injury.
  • Page 21 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.
  • Page 22 Troubleshooting 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. 35 PSI Recommended for single cylinder 31.5 24.5 17.5...
  • Page 23 Air Cleaner/Intake AIR CLEANER NOTE: Operating engine with loose or damaged air cleaner components could cause premature These systems are CARB/EPA certifi ed and components wear and failure. Replace all bent or damaged should not be altered or modifi ed in any way. components.
  • Page 24 fi tting on crankcase or valve cover. Low permeation fuel line must be installed on carbureted Kohler Co. engines to maintain EPA and CARB 4. Attach new fuel pump using screws. Torque screws regulatory compliance.
  • Page 25 Fuel System CARBURETORS Gasoline is extremely fl ammable and its vapors can WARNING explode if ignited. Store gasoline only in approved Explosive Fuel can cause fi res and severe containers, in well ventilated, unoccupied buildings, away burns. from sparks or fl ames. Spilled fuel could ignite if it comes in contact with hot parts or sparks from ignition.
  • Page 26 Fuel System Keihin One-Barrel Carburetor Components Engines in this series are equipped with Keihin fi xed main jet carburetors. CH18-740 engines use a one- barrel carburetor. Most applications use a fuel shut-off solenoid installed in place of fuel bowl retaining screw, and also contain an accelerator pump.
  • Page 27 Fuel System Troubleshooting-Carburetor Related Causes Condition Possible Cause Conclusion Engine starts hard, runs rough, or Low idle fuel mixture (some models)/ Adjust low idle speed tab, then adjust stalls at idle speed. speed improperly adjusted. low idle fuel needle. Engine runs rich (indicated by black, Clogged air cleaner.
  • Page 28 Fuel System 2. Release governor lever and check that throttle lever Carburetor Circuits is in idle position. Turn governed idle adjustment Float screw to obtain equipment manufacturer’s Fuel level in bowl is maintained by fl oat and fuel inlet recommended idle speed (1500-1800 RPM). Some needle.
  • Page 29 Fuel System High Speed (RPM) Adjustment 3. For two-barrel carburetor, remove fl oat pin screw, 1. With engine running, move throttle control to fast. fl oat, pin, and inlet needle. Seat for inlet needle is not serviceable and should not be removed. 2.
  • Page 30 Fuel System 12. Insert new bushing through new choke lever from 21. Install large fl at retaining washer (if equipped) and outside and start bushing in outer shaft bore. secure with mounting screw, attaching ground lead if Position choke lever so protruding boss on originally secured by screw.
  • Page 31 (1219 meters) or above, a high altitude carburetor bending fl oat tab. kit is required. To obtain high altitude carburetor kit information or to fi nd a Kohler authorized dealer, visit One-Barrel Carburetor Float Detail KohlerEngines.com or call 1-800-544-2444 (U.S. and Canada).
  • Page 32 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 rotary stepper motor. Power and ground are supplied to master CDI &...
  • Page 33 Fuel System connected to review operation or look for error eChoke System Standard Checks 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 (on next page).
  • Page 34 Fuel System 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.
  • Page 35 Fuel System Troubleshooting eChoke Related Causes ™ Condition Possible Cause Conclusion Engine starts hard, runs rough, or Choke not closing/moving Stepper motor/bracket/link assembly stalls at idle speed. a. Broken or missing link. must allow for full travel, make sure link is located properly and connected.
  • Page 36 Fuel System Replace Rotary Stepper Motor 4. Position new rotary stepper motor on bracket with leads down, insert rivet (as shown) and use rivet tool to pull rivet until tight. Install second rivet to secure motor to bracket. 5. Position rotary stepper motor/bracket/rivet assembly on carburetor and reinstall lever on motor.
  • Page 37 Governor System GOVERNOR These engines are equipped with an electronic governor or a mechanical governor. ELECTRONIC GOVERNOR Digital Linear Actuator (DLA) Energizing bi-directional digital linear actuator coils in Electronic Governor System proper sequence, causes threaded shaft to move out Engines with electronic governor are equipped with of, or back into rotor, in precise linear increments.
  • Page 38 Governor System Adjustment Troubleshooting DLA Details Engine Starts But Will Not Continue to Run 1. Check linkage connection between DLA and throttle plate. 2. Verify throttle plate is opened during start procedure. Engine is unlikely to start if throttle plate is not opened.
  • Page 39 Governor System Ohms Tests GCU/Harness Diagnostics and Troubleshooting 1. Remove GCU and unplug wiring harness. NOTE: It is important to use proper sized probes to These two tests are for measuring resistance of DLA perform these tests. Probes that are incorrect circuit that sends a signal to GCU.
  • Page 40 Governor System Speed Control Input GCU Designs Red Wire with Yellow Tracer. This connection is either a single wire red with yellow tracer or a 6 pin connector body with a red wire with yellow tracer. First Design GCU Second Design GCU Green LED Light Yellow LED Light F Fourth (Latest) Design...
  • Page 41 Governor System Several diff erent GCU designs have been used. First design (24 584 40-S and earlier) had a black potting compound, did not have LED lights, and did not store diagnostic trouble codes. See page 42 for troubleshooting detail and a basic electrical diagram for this GCU design. See pages 50-52 for a troubleshooting fl...
  • Page 42 Governor System FIRST DESIGN GCU Troubleshooting Electronic Governor Failure Condition Possible Causes Equipment Observations Inspection/Testing Target/Selected Loss of GCU power When connection is lost, no DLA Test GCU power (red/B+) Speed not (B+ or Ground). movement will be seen. When wire for supply voltage and Maintained (Potentially...
  • Page 43 Governor System SECOND DESIGN GCU Troubleshooting Electronic Governor Failure Condition Possible Causes Equipment Observations Inspection/Testing Target/Selected Loss of GCU power When connection is lost, no DLA Test for GCU power by Speed not (B+ or Ground). movement will be seen. When turning key to ON position Maintained (Potentially...
  • Page 44 Governor System SECOND DESIGN GCU Blink Codes LED Diagnostics Response Failure Condition Possible Causes Response Time Yellow LED Green LED Overspeed (Over External noise on ignition input Ground to kill, Flashing 4500 RPM for 0.5 close carb throttle seconds Frozen carb throttle plate seconds sustained) plate DLA failure...
  • Page 45 Governor System SECOND DESIGN GCU Basic Electrical Diagram of Electronic Governor System Kill Tab (Speed Signal) Speed Signal Power Green LED Light Yellow LED Light Device Ground Ignition Module DLA Driver Controls Application Supplied Speed Control Input Operation Input Voltage: 0-1 Volts at Idle/9+ Volts at High Speed.
  • Page 46 Governor System THIRD AND FOURTH DESIGN GCU Troubleshooting Electronic Governor Failure Condition Possible Causes Equipment Observations Inspection/Testing Target/Selected Loss of GCU power When connection is lost, no DLA Test for GCU power by Speed not (B+ or Ground). movement will be seen. When turning key to ON position Maintained (Potentially...
  • Page 47 Governor System THIRD AND FOURTH DESIGN GCU Blink Codes for Software Running Codes - Activated when engine is running. LED Diagnostics Response Failure Condition Possible Causes Response Time Yellow LED Green LED Running Normally None BLINKS BLINKS RPM Too High Mechanical bindage None BLINKS...
  • Page 48 Governor System THIRD DESIGN GCU Basic Electrical Diagram of Electronic Governor System Kill Tab (Speed Signal) Speed Signal Power Green LED Light Yellow LED Light Device Ground Ignition Module DLA Driver Controls Application Supplied Speed Control Input Operation Input Voltage: 0-1 Volts at Idle/9+ Volts at High Speed.
  • Page 49 Governor System FOURTH (LATEST) DESIGN GCU Basic Electrical Diagram of Electronic Governor System Kill Tab (Speed Signal) Power Speed Signal Green LED Light Yellow LED Light Ignition Module Device Ground DLA Driver Controls Application Supplied Speed Control Input Operation Input Voltage: 0-1 Volts at Idle/9+ Volts at High Speed.
  • Page 50 Governor System Electronic Governor Troubleshooting Flow Chart Turn off key switch. Do Not Touch Digital Linear Actuator (DLA) NOTE: DLA is not a solenoid. It is a precision electronic motor. Do not exert force to center clevis shaft! Visually inspect DLA and Linkage. See illustrations on pages 37 and 38. Confi...
  • Page 51 Engine speed increases Operation Input Voltage: (if it was at low speed). 0-1 Volts at Idle/9+ Volts at High Speed. Kohler electronic governor system tests OK. Test Fail Pass control system of equipment. Refer to Equipment Manufacturer’s diagnostic procedures for control system.
  • Page 52 Governor System Electronic Governor Troubleshooting Flow Chart (Continued) Inspect wiring harness for broken wire or bad connections. (Repair/Replace as required). Test supply ground circuit to GCU using a continuity OHM/tester. Refer to page 39. Test supply voltage to GCU using volt meter. Refer to page 39 (battery voltage +/- 1 volt) Note: Prevent Damage to Connector.
  • Page 53 Governor System MECHANICAL GOVERNOR A centrifugal fl yweight mechanical governor is designed to hold engine speed constant under changing load conditions. Governor gear/fl yweight mechanism is mounted inside crankcase on closure plate, and is driven off gear on camshaft. Governor Components H Inside Engine Throttle Lever Throttle Linkage...
  • Page 54 Governor System Sensitivity Adjustment Governor sensitivity is adjusted by repositioning governor spring in holes of governor lever. If speed surging occurs with a change in engine load, governor is set too sensitive. If a big drop in speed occurs when normal load is applied, governor should be set for greater sensitivity and adjust as follows: 1.
  • Page 55 Lubrication System This engine uses a full pressure lubrication system which 3. If oil is low on indicator, add oil up to top of indicator delivers oil under pressure to crankshaft, camshaft, mark. connecting rod bearing surfaces, and hydraulic valve 4.
  • Page 56 Lubrication System OIL SENTRY (if equipped) ™ 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.
  • Page 57 Electrical System SPARK PLUGS Inspection Inspect each spark plug as it is removed from cylinder CAUTION head. Deposits on tip are an indication of general Electrical Shock can cause injury. condition of piston rings, valves, and carburetor. Do not touch wires while engine is running. Normal and fouled plugs are shown in following photos: Normal Spark Plug Component and Details...
  • Page 58 Electrical System Carbon Fouled 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.
  • Page 59 Electrical System ELECTRONIC IGNITION SYSTEMS CDI/MDI Ignition Module Identifi cation Ignition System Components CDI Ignition Module MDI Ignition Module These systems use a capacitive discharge (CD) coil. Kill Switch/ With CDI fi xed timing, ignition timing and spark remains Off Position of Air Gap constant regardless of engine speed.
  • Page 60 Electrical System Wiring Diagram-15/20/25 Amp Regulated Battery Charging System with CDI/MDI KohlerEngines.com 24 690 06 Rev. O...
  • Page 61 Electrical System Spark Plug(s) Oil Pressure Switch Oil Sentry (Green) White Kill ™ Flywheel Stator Rectifi er-Regulator Ignition Module CDI/MDI Ignition Assembly Connector Solenoid Shift Starter Rectifi er-Regulator Oil Sentry Kill (Green) Violet B+ Assembly ™ Starter Solenoid Tang Starter Solenoid Stud Fuse Blue Alternate Ignition Kill...
  • Page 62 Electrical System 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.
  • Page 63 Electrical System Wiring Diagram-15/20/25 Amp Regulated Battery Charging System with Variable Ignition Timing SMART- SPARK ™ 24 690 06 Rev. O KohlerEngines.com...
  • Page 64 Electrical System Oil Pressure Switch Oil Sentry (Green) Spark Plug(s) Kill ™ Flywheel Stator 22, 25 HP Smart- Trigger Ignition Module Assembly Spark Ignition ™ Yellow on Analog Module Speed Brown Yellow SAMs Pink on Digital Advance 22, 25 HP SAMs Rectifi...
  • Page 65 Electrical System Condition Possible Cause Conclusion Both cylinders have good spark but Spark Plug(s) Install new spark plug(s) and retest engine runs poorly or existing plug engine performance. condition is questionable. If problem persists, check for timing advance. 1 cylinder has good spark and other Ignition Test ignition modules and cylinder has no or intermittent spark.
  • Page 66 Electrical System Test Smart-Spark Ignition Modules and Smart-Spark Ignition Module Resistance Table ™ ™ Connections 24 584 03 24 584 15-S NOTE: Resistance values apply only to modules that have been on a running engine. New service 24 584 11 24 584 36-S modules may have higher resistance until they (1 11/16 in.
  • Page 67 Electrical System 6. Reattach lead wires to ignition module(s), noting if resistance is felt, indicating a snug fi t between male and female terminals. If any connections do not feel snug, disconnect lead, lightly pinch female terminal with a pliers, and recheck fi...
  • Page 68 Electrical System To replace battery, remove outer set of screws on 1. Check SAM part number stamped on end of faceplate and carefully lift panel from body. Unplug housing. connector and pull battery (with mounting tape) off back a. If it is an ASAM (24 584 09 or 24 584 10), of tester.
  • Page 69 Electrical System Wiring Diagram-15/20/25 Amp Regulated Battery Charging System with DSAI Ignition and Key Switch 24 690 06 Rev. O KohlerEngines.com...
  • Page 70 Electrical System Black (Ground) Intake Green (Oil Sentry Oil Pressure Switch Manifold Mounting Black ™ Pulse Signal Lead) Screw White Spark Plug(s) Black (Ground) Flywheel Stator Red (B+) White (DSAI Kill) Module Screw Assembly White (AC Charging Rectifi er-Regulator DSAI Module Rectifi...
  • Page 71 Electrical System Condition Possible Cause Conclusion Both cylinders have good spark but Spark Plug(s) Install new spark plug(s) and retest engine runs poorly or existing plug engine performance. condition is questionable. If problem persists, check for?? 1 cylinder has good spark and other Ignition Test ignition modules and cylinder has no or intermittent spark.
  • Page 72 Electrical System 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.
  • Page 73 Electrical System 15/20/25 Amp Battery Charging Systems NOTE: Always zero digital volt-ohm meter (DVOM) on each scale before testing to ensure accurate readings. Voltage test should be made with engine running at specifi c test condition noted. Battery should be checked for state of charge (non-operating voltage 12.5 VDC or lower, battery should be charged or replaced).
  • Page 74 Electrical System Wiring Diagram-3 Amp Unregulated Battery Charging System/70 Watt Lighting Optional Oil Optional Oil Ground-To-Kill Sentry Switch Sentry Switch 12 V. Battery Light Lead (White) ™ ™ (Shutdown) (Indicator Light) Optional Ground Optional Fuse Key Switch Ammeter Blue Solenoid Lights Starter Yellow...
  • Page 75 Electrical System 3 Amp/70 Watt Lighting Stator 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. To test charging system for no charge to battery: To test charging system for no lights: 1.
  • Page 76 Starter System 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.
  • Page 77 4. Clean splines on drive shaft thoroughly with solvent. Dry splines thoroughly. 5. Apply a small amount of Kohler electric starter drive lubricant, to splines. Use of other lubricants may cause drive pinion to stick or bind.
  • Page 78 A brush holder tool can easily be made 5. Install thru bolts and tighten securely. from thin sheet metal. 6. Lubricate drive shaft with Kohler starter drive 1. Remove brush springs from pockets in brush holder. lubricant. Install drive components following 2.
  • Page 79 Starter System SOLENOID SHIFT ELECTRIC STARTERS Nippondenso Starters Solenoid Shift Starter Components Starter Disassembly NOTE: When removing lever and armature be careful not to lose thrust washer. 1. Disconnect lead wire from solenoid. 2. Remove nuts securing solenoid, and remove solenoid from starter assembly.
  • Page 80 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).
  • Page 81 Starter System 10. Starter reassembly when replacing brushes/brush Starter Reassembly holder assembly: NOTE: Always use a new retainer. Do not reuse old a. Hold starter assembly vertically on end housing, retainers that have been removed. and carefully position assembled brush holder NOTE: Correctly installed, center pivot section of drive assembly, with supplied protective tube, against lever will be fl...
  • Page 82 Starter System 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.
  • Page 83 Starter System RETRACTABLE STARTERS Remove Starter 1. Remove screws securing starter to blower housing. WARNING 2. Remove starter assembly. Uncoiling Spring can cause severe injury. Rope Replacement Wear safety goggles or face protection when servicing retractable starter. NOTE: Do not allow pulley/spring to unwind. Enlist aid of a helper if necessary.
  • Page 84 Starter System Pawls (dogs) Replacement 1. Install a clamp to hold pulley in starter housing and prevent if from rotating. 2. Remove center screw, washer, and pawl retainer. 3. Note position of pawls and pawl springs before removing. Remove pawls, pawls springs, brake spring and brake washer from pulley.
  • Page 85 Clutch WET DISC TYPE CLUTCH (if equipped) Wet Disc Type Clutch Components Shifting Lever Gasket Seal Shaft (Yoke) Nameplate Clutch Housing Adjusting Ring Driven Member Bearing Release Release Sleeve Pressure Plate Pilot Bearing Assembly Adjusting Lock Clutch Assembly Power Shaft Retaining Rings Yoke Roll Pin...
  • Page 86 Clutch Service 1. Release clutch and remove nameplate. Using a On this clutch type, an oil splash type lubrication system large screwdriver, turn adjusting ring clockwise, one is used. Proper oil level must be maintained to provide notch at a time, until fi rm pressure is required to effi...
  • Page 87 Disassembly/Inspection and Service WARNING Before working on engine or equipment, disable engine as Accidental Starts can cause severe injury or follows: 1) Disconnect spark plug lead(s). 2) Disconnect death. negative (–) battery cable from battery. Disconnect and ground spark plug lead(s) before servicing.
  • Page 88 Disassembly/Inspection and Service Clean all parts thoroughly as engine is disassembled. Remove Fuel Pump Only clean parts can be accurately inspected and gauged for wear or damage. There are many WARNING commercially available cleaners that will quickly remove grease, oil, and grime from engine parts. When such a Explosive Fuel can cause fi...
  • Page 89 Disassembly/Inspection and Service Disconnect stepper motor connector from wiring Remove Throttle and Choke Controls harness. Control Bracket Components 3. One-barrel carburetor models only: Remove carburetor mounting screws. Two-barrel carburetor models only: If required use nuts locked together and remove carburetor mounting studs on starter side of intake manifold and one stud on oil fi...
  • Page 90 Disassembly/Inspection and Service 4. Pry under protruding edge of breather cover with a Remove Inner Baffl es and Breather Cover screwdriver to break RTV or gasket seal. Do not pry Inner (valley) baffl es are attached at one corner using on sealing surfaces as it could cause damage same fasteners as breather cover.
  • Page 91 Disassembly/Inspection and Service cylinder reconditioning is necessary. Once removed, 1. Remove screws, rocker arm pivots and rocker arms they must be replaced. from cylinder head. Note screw color for reassembly. 2. Mark position of push rods as either intake or 2.
  • Page 92 Check base surface of hydraulic lifters for wear or Replace valves found to be in bad condition. damage. If lifters need to be replaced, apply a liberal coating of Kohler lubricant to base of each new lifter Valve Guides before it is installed.
  • Page 93 Use a hook-end tool next to post and pull Inspect ring gear for cracks or damage. Kohler does not outward to separate small metal retainers. Then provide ring gear as a serviceable part. Replace fl ywheel unsnap fan from remaining mounting posts.
  • Page 94 Disassembly/Inspection and Service Crankcase Components Oil Seal Closure Plate (Style A) Gerotor Gear (Style A) Dipstick Tube Oil Pick-Up Tube Oil Pump Assembly Governor Gear Shaft Governor Gear (Style A) (Style A) Camshaft Piston Pin Piston Ring Set Piston Pin Retainer Connecting Rod End Piston (Style B) Connecting Rod...
  • Page 95 Disassembly/Inspection and Service Inspection Governor Gear Assembly Inspect governor gear teeth. Replace gear if it is worn, chipped, or if any teeth are missing. Inspect governor Governor Shaft Component and Details weights. They should move freely in governor gear. Disassembly NOTE: Governor gear is held onto shaft by small molded tabs in gear.
  • Page 96 Disassembly/Inspection and Service Oil Pump Assembly (Style A) Oil Pump Assembly (Style B) Oil pump is mounted inside closure plate. If service is Oil pump is mounted inside closure plate. If service is required, continue with Disassembly, Inspection, and required, continue with Disassembly, Inspection, and Reassembly.
  • Page 97 Disassembly/Inspection and Service Ring failure is usually indicated by excessive oil Remove Connecting Rods with Pistons and Rings consumption and blue exhaust smoke. When rings fail, NOTE: If a carbon ridge is present at top of either oil is allowed to enter combustion chamber where it is cylinder bore, use a ridge reamer tool to remove burned along with fuel.
  • Page 98 Disassembly/Inspection and Service Piston Style B Install New Piston Rings 1. Cylinder bore must be de-glazed before service ring Piston Ring Orientation 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.
  • Page 99 Disassembly/Inspection and Service Carefully pull crankshaft from crankcase. Note thrust Connecting Rods washers and shims if used. Off set, stepped-cap connecting rods are used in all Inspect gear teeth of crankshaft. If teeth are badly worn, these engines. chipped, or some are missing, replacement of crankshaft Inspection and Service will be necessary.
  • Page 100 Install new seal to depth shown using a seal installer. NOTE: Kohler pistons are custom-machined to exacting tolerances. When oversizing a cylinder, it should Remove Flywheel End Oil Seal be machined exactly 0.25 mm (0.010 in.) or 0.50 mm (0.020 in.) over new diameter (refer to...
  • Page 101 Disassembly/Inspection and Service 4. After resizing, check bore for roundness, taper, and Measuring Piston-to-Bore Clearance size. Use an inside micrometer, telescoping gauge, Piston Detail or bore gauge to take measurements. These measurements should be taken at 3 locations in cylinder–at top, middle, and bottom. There are 2 measurements that should be taken (perpendicular to each other) at all 3 locations.
  • Page 102 Reassembly Crankcase Components Oil Seal Closure Plate (Style A) Gerotor Gear (Style A) Dipstick Tube Oil Pick-Up Tube Oil Pump Assembly Governor Gear Shaft Governor Gear (Style A) (Style A) Camshaft Piston Pin Piston Ring Set Piston Pin Retainer Connecting Rod End Piston (Style B) Connecting Rod Crankshaft...
  • Page 103 Reassembly NOTE: Cylinders are numbered on crankcase. Make Install Governor Cross Shaft sure to install piston, connecting rod and end 1. Lubricate governor cross shaft bearing surfaces in cap into its appropriate cylinder bore as crankcase with engine oil. previously marked at disassembly. Do not mix end caps and connecting rods.
  • Page 104 Reassembly Determining Camshaft End Play Thrust Bearing, Washer and Shim 1. Install shim removed during disassembly onto Thrust Bearing, Washer, and Shim Sequence camshaft. 2. Position camshaft end play checking tool on camshaft. 3. Apply pressure on camshaft end play checking tool (pushing camshaft toward crankshaft).
  • Page 105 Reassembly Remove closure plate. If end play requires adjustment, Install Closure Plate Assembly remove original spacer and install appropriate size shim spacer in its place. Then follow procedure under Install Sealant Pattern and Torque Sequence Closure Plate Assembly. Install Closure Plate Oil Seal Oil Seal Depth RTV sealant is used as a gasket between closure plate and crankcase.
  • Page 106 Reassembly Flywheel/Ignition Components Debris Screen Flywheel Screw Washer Flywheel Magnet Stator Ignition Module Backing Plate Woodruff Key Spring Washer Spacer Metal Debris Screen Ring Support Metal Debris Screen Washer Assembly NOTE: Make sure fl ywheel key is installed properly in Install Stator and Backing Plates keyway.
  • Page 107 Reassembly Install Plastic Debris Screen Install Supports for Metal Debris Screen 1. If a metal debris screen is used, with threaded CAUTION individual supports, install a spacer washer on external threads. Apply Loctite (removable) ® ® Failure to utilize or reassemble debris screen onto threads.
  • Page 108 Reassembly b. Thread opposite end of stud with preapplied Assemble Cylinder Heads locking compound into crankcase until specifi ed Prior to installation, lubricate all components with engine height from crankcase surface is achieved. oil, paying particular attention to lip of valve stem seal, When threading in studs, use a steady tightening valve stems and valve guides.
  • Page 109 Reassembly Install Spark Plugs Install Intake Manifold 1. Check gap using wire feeler gauge. Adjust gap to Torque Sequence 0.76 mm (0.030 in.). 2. Install plug into cylinder head. 3. Torque plug to 27 N·m (20 ft. lb.). Install Ignition Modules 1.
  • Page 110 Reassembly External Engine Components Intake Manifold Gasket Carburetor Outer Baffl e Breather Tube Oil Sentry Breather Cover Breather Gasket ™ Inner Baffl e Breather Reed Filter Electric Starter Lifting Bracket Fixed Guard Blower Housing Debris Shield Wire Clip Oil fi lter Nipple Oil Cooler Valve Cover Fuel...
  • Page 111 Reassembly 3. Position outer baffl es and loosely start mounting Install Breather Cover and Inner Baffl es screws. M6 screws go into back of cylinders. Short Breather Cover Torque Sequence M5 screws go into lower holes closest to blower housing. Short screw on oil fi lter side is also used to mount wire harness clip.
  • Page 112 Reassembly 4. Connect ground lead and fuel solenoid lead as Install Fuel Pump equipped. WARNING Control Bracket Components 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.
  • Page 113 Reassembly 6 mm Governor Lever and Hole Position/RPM Chart Governor Lever Hole Position (6 mm) Governor Gov. Lever High Idle RPM Spring Color Hole No. Code 3801-4000 Clear 3601-3800 Clear 3451-3600 Clear 3301-3450 Clear 3101-3300 Purple 2951-3100 Purple 2800-2950 Purple 3750* Clear 3150*...
  • Page 114 Reassembly 8 mm Governor Lever and Hole Position/RPM Chart for CH20-CH740 Engines Non-Accelerator Pump Intended Maximum RPM Accelerator Pump Carburetor Governor Shaft Carburetor Confi guration High Idle Spring Color Hole No. Spring Color Hole No. 3744 3600 Orange Needle Bearing 3120 3000 Clear...
  • Page 115 Reassembly Torque Specifi cations-Covers Install Oil Filter and Fill Crankcase with Oil Gasket/RTV 3.4 N·m (30 in. lb.) NOTE: Make sure both oil drain plugs are installed and Black O-ring torqued to specifi cations to prevent oil leakage. w/shoulder screws 5.6 N·m (50 in.
  • Page 116 © 2021 by Kohler Co. All rights reserved. KohlerEngines.com 24 690 06 Rev. O...

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