Kohler RH255 Service Manual
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Kohler RH255 Service Manual

2000 series
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RH255, RH265
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
12
Tools and Aids
15
Troubleshooting
19
Air Cleaner/Intake
20
Fuel System
24
Governor System
25
Lubrication System
26
Electrical System
32
Starter System
36
Disassembly/Inspection and Service
45
Reassembly
18 690 06 Rev. --
KohlerEngines.com
1

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  • Page 1 RH255, RH265 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 cations...

  • Page 2: Safety Precautions

    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: Maintenance Instructions

    Perform these procedures more frequently under severe, dusty, dirty conditions. 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). 18 690 06 Rev. --...

  • Page 4: Oil Recommendations

    OIL RECOMMENDATIONS STORAGE If engine will be out of service for 2 months or more We recommend use of Kohler oils for best performance. follow procedure below. Other high-quality detergent oils (including synthetic) of API (American Petroleum Institute) service class SJ 1.

  • Page 5: Specifications

    Specifi cations Engine Dimensions Dimensions in millimeters. Inch equivalents shown in [ ]. 10.50 FUEL CAP [0.413] REMOVAL 329.53 [12.974] 297.37 [11.707] 65.05 [2.561] 32.53 106.00 [1.281] [4.173] METRIC FLANGE: 4X M8 X 1.25-6H 15.00 [0.591] SAE FLANGE: 4X 5/16-24 UNF-2B 15.00 [0.591] 32.53 [1.281]...

  • Page 6: Engine Identification Numbers

    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 7: Clearance Specifications

    Specifi cations TORQUE SPECIFICATIONS RH255, RH265 Fuel Tank Mounting Screw 4.5 N·m (40 in. lb.) Outlet Filter Fitting 2.0 N·m (17.7 in. lb.) Governor Arm Nut 7 N·m (62 in. lb.) Throttle Control Lever Nut 4.5-6 N·m (40-53 in. lb.)
  • Page 8 Specifi cations CLEARANCE SPECIFICATIONS RH255, RH265 Crankcase Governor Cross Shaft Bore I.D. 6.000/6.018 mm (0.2362/0.2369 in.) Max. Wear Limit 6.037 mm (0.2377 in.) Crankshaft End Play (free) 0.025/0.703 mm (0.0010/0.028 in.) Bore (in crankcase) 51.961/51.991 mm (2.0457/2.0469 in.) Bore (in closure plate) 51.961/51.991 mm (2.0457/2.0469 in.)
  • Page 9 Specifi cations CLEARANCE SPECIFICATIONS RH255, RH265 Ignition Spark Plug Gap 0.76 mm (0.030 in.) Module Air Gap 0.254 mm (0.0100 in.) Piston, Piston Rings, and Piston Pin Piston-to-Piston Pin Running Clearance 0.006/0.018 mm (0.0002/0.0007 in.) Piston Pin Bore I.D. 18.002/18.008 mm (0.7087/0.7090 in.) Max.
  • Page 10 Specifi cations CLEARANCE SPECIFICATIONS RH255, RH265 Valves and Valve Lifters Intake Valve Stem-to-Valve Guide Running Clearance 0.020/0.044 mm (0.008/0.0017 in.) Exhaust Valve Stem-to-Valve Guide Running Clearance 0.030/0.054 mm (0.0011/0.0021 in.) Intake Valve Stem O.D. 5.480 mm (0.2157 in.) Max. Wear Limit 5.32 mm (0.2094 in.)

  • Page 11: General Torque Values

    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 12: Tools And Aids

    Here is a list of tools and their source. SEPARATE TOOL SUPPLIERS Kohler Tools SE Tools Design Technology Inc. Contact your local Kohler source of 415 Howard St. 768 Burr Oak Drive supply. Lapeer, MI 48446 Westmont, IL 60559...
  • Page 13 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 Valve Guide Service Kit (Courage, Aegis, Command, OHC) SE Tools KLR-82415 For servicing worn valve guides.
  • Page 14 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 15: Troubleshooting Guide

    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 16 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 17: Crankcase Vacuum Test

    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. Engine exhaust gases contain poisonous carbon Keep hands, feet, hair, and clothing away from all monoxide.

  • Page 18: Compression Test

    Troubleshooting COMPRESSION TEST For Command Twins: 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 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 19: Air Cleaner/Intake

    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 20: Fuel Filter

    Filter is in tank outlet fi tting. Remove fuel tank from Low permeation fuel line must be installed on carbureted engine. Remove outlet fi tting from fuel tank. Check Kohler Co. engines to maintain EPA and CARB condition and replace if required. Torque fi tting to regulatory compliance.
  • Page 21 Fuel System CARBURETOR 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 22 Fuel System Troubleshooting-Carburetor Related Causes Condition Possible Cause Conclusion Engine starts hard, runs rough, or Low idle speed improperly adjusted. Adjust idle speed screw or clean stalls at idle speed. carburetor. Engine runs rich (indicated by black, Clogged air cleaner. Clean or replace air cleaner.
  • Page 23 WARNING 1219 meters (4000 ft.). To obtain high altitude kit information or to fi nd a Kohler authorized dealer visit KohlerEngines.com or call 1-800-544-2444 (U.S. and Accidental Starts can cause severe injury or Canada).

  • Page 24: Governor System

    Governor System GOVERNOR Governor Components Control Assembly Governor Spring Throttle Link Dampening Spring Throttle Control Lever Governor Lever Washer Governor Gear Governor Gear Shaft Governed speed setting is determined by position of ● When load is applied and engine speed and governor throttle control.

  • Page 25: Lubrication System

    Lubrication System These engines use a splash lubrication system, supplying necessary lubrication to crankshaft, camshaft, connecting rod and valve train components. Lubrication Components Dipstick/Oil Fill Plug Oil Fill Plug (Optional) Oil Drain Plug OIL RECOMMENDATIONS CHANGE OIL Refer to Maintenance. Change oil while engine is warm.

  • Page 26: Electrical System

    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 27: Electronic Ignition System

    Electrical System Carbon Fouled ELECTRONIC IGNITION SYSTEM Inductive Discharge Ignition System Components Soft, sooty, black deposits indicate incomplete combustion caused by a restricted air cleaner, over rich carburetion, weak ignition, or poor compression. Overheated Kill Switch/Off Position Air Gap 0.254 mm of Switch (0.010 in.) Flywheel...
  • Page 28 Electrical System NOTE: Observe following guidelines to avoid damage to Electronic Ignition System Tests electrical system and components: 1. Disconnect cap from spark plug and attach it to ● Make sure battery polarity is correct. A negative (-) terminal end of spark tester. Attach tester spring clip ground system is used.
  • Page 29 Electrical System Wiring Diagram-3 Amp Charging System, Rectifi ed Only Diode Stator Ignition Module Spark Plug Ignition Switch Starter Motor Relay Battery Fuse 12 Volt Battery 18 690 06 Rev. -- KohlerEngines.com...
  • Page 30 Electrical System Wiring Diagram-10 Amp Charging System, with Rectifi er-Regulator Rectifi er-Regulator Stator Ignition Module Spark Plug Ignition Switch Starter Motor Relay Battery Fuse 12 Volt Battery KohlerEngines.com 18 690 06 Rev. --...
  • Page 31 Electrical System 3/10 Amp Battery Charging Systems NOTE: Zero ohmmeters on each scale to ensure accurate readings. Voltage tests should be made with engine running at 3600 RPM - no load. Battery must be fully charged. Check specifi c gravity of battery. If low, recharge or replace battery as necessary.

  • Page 32: Starter System

    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 33 Starter System 4. Use a known, good, fully-charged battery and jumper cables to test starter motor. Be sure transmission is in neutral and PTO is OFF. Remove heavy lead from post terminal on starter. Connect one end of positive jumper cable to post terminal and connect other end to positive terminal of battery.

  • Page 34: Retractable Starters

    Starter System RETRACTABLE STARTERS WARNING Retractable starters contain a powerful, recoil spring that is under tension. Always wear safety goggles when servicing Uncoiling Spring can cause severe injury. retractable starters and carefully follow instructions in Wear safety goggles or face protection when Retractable Starter for relieving spring tension.
  • Page 35 Starter System 4. Remove nuts securing blower housing/retractable Install Blower Housing/Retractable Starter starter assembly to crankcase studs. Assembly 5. Remove blower housing/retractable starter 1. Position blower housing/retractable starter assembly assembly. on crankcase studs, while feeding fuel line through two clamps at top of housing. Secure with nuts. Rope Replacement Torque nuts to 8 N·m (70.8 in.

  • Page 36: Disassembly/Inspection And Service

    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 37 Disassembly/Inspection and Service 3. If engine has evap air cleaner base, disconnect evap Drain Oil From Crankcase hose from base. 1. Remove 1 oil drain plug and dipstick/oil fi ll plug. 4. Remove air cleaner base and base gasket. 2. Allow ample time for oil to drain from crankcase. 5.
  • Page 38 Disassembly/Inspection and Service Slide carburetor off mounting studs while disconnecting Remove Carburetor throttle linkage and dampening spring. Remove carburetor to insulator gasket, insulator, and insulator to WARNING cylinder head gasket. Explosive Fuel can cause fi res and severe Remove Electric Starter (if equipped) burns.
  • Page 39 Disassembly/Inspection and Service Remove Valves 2. Remove and replace intake valve stem seal whenever cylinder head is serviced or disassembled. NOTE: Mark location of any part removed that will be reused. 1. Supporting head of valve from below, depress valve keeper and valve spring until keeper can be released from valve stem.
  • Page 40 Disassembly/Inspection and Service Hard starting, or loss of power accompanied by high Flywheel/Ignition Components 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.
  • Page 41 Disassembly/Inspection and Service Crankcase Components Closure Plate Oil Seal Closure Plate Camshaft Crankshaft End Cap Connecting Rod Piston Pin Retainer Piston Piston Pin Piston Ring Set Tappet Governor Cup Governor Washer Governor Shaft Governor Gear Governor Cross Shaft Crankcase Oil Seal Dowel Pin Remove Closure Plate Remove Camshaft and Valve Tappets...
  • Page 42 Disassembly/Inspection and Service Automatic Compression Release (ACR) 6. Engines with ACR can be started with spark plugs that are worn or fouled. Engines without ACR are ACR Operation Details more diffi cult to start with those same spark plugs. Remove Piston, Connecting Rod, and Crankshaft NOTE: If a carbon ridge is present at top of cylinder bore, use a ridge reamer to remove it before attempting to remove piston.
  • Page 43 Disassembly/Inspection and Service Replacement ring sets are also available separately Install New Piston Rings for STD 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 deglazed before service ring sets are used.
  • Page 44 Disassembly/Inspection and Service 3. Top compression ring (top groove): Install top Crankcase compression ring using a piston ring expander tool. Make sure identifi cation mark is up or colored dye Cylinder Bore Details stripe (if contained) is left of end gap. Adjust ring gaps.
  • Page 45 Reassembly Crankcase Components Closure Plate Oil Seal Closure Plate Camshaft Crankshaft End Cap Connecting Rod Piston Pin Retainer Piston Piston Pin Piston Ring Set Tappet Governor Cup Governor Washer Governor Shaft Governor Gear Governor Cross Shaft Crankcase Oil Seal Dowel Pin Oil Seal Depth Outer Surface NOTE: Make sure engine is assembled using all...
  • Page 46 Reassembly Install Governor Assembly 3. Install and stagger piston rings in grooves. 4. Lubricate cylinder bore, piston, piston pin, and piston 1. Install governor shaft through gear and add thrust washer to shaft. rings with engine oil. Compress rings using a piston ring compressor.
  • Page 47 Reassembly 4. Install closure plate to crankcase. Carefully seat Install Closure Plate ends of camshaft and balance shaft into their mating bearings. Rotate crankshaft slightly to help engage Torque Sequence governor gear teeth. 5. Install screws securing closure plate to crankcase. Torque screws in sequence shown to 24 N·m (212 in.
  • Page 48 Reassembly NOTE: Before installing fl ywheel make sure crankshaft Install Ignition Module taper and fl ywheel hub bore are clean, dry, and NOTE: Ensure ignition module is correctly oriented. completely free of lubricants. Presence of lubricants can cause fl ywheel to be over 1.
  • Page 49 Reassembly Assemble Cylinder Head Install Valve Cover NOTE: Engine utilizes a valve stem seal on intake Sealant Pattern valve. Always use a new seal when valves are installed in cylinder head. Never reuse an old seal. 1. Install valves into their respective positions. 2.
  • Page 50 Reassembly Blower Housing/Control Panel Components Governor Lever Governor Spring Throttle Link Blower Housing/ Dampening Spring Control Assembly Carburetor Retractable Starter Assembly 3. Mount control panel to crankcase and secure with Install Throttle Plate screws. Ensure ground wires are placed between Install throttle plate with screws.
  • Page 51 Reassembly External Engine Components Oil Drain Plug Dipstick/Oil Fill Plug Fuel Tank Fuel Tank Cap Muffl er Assembly Breather Tube Air Cleaner Base Spit Cup Cover Foam Element Paper Element Air Cleaner Cover Install Fuel Tank Install Muffl er and Heat Shield Assembly 1.
  • Page 52 Reassembly Install Air Cleaner Base, Element, and Cover 1. Install air cleaner base gasket onto carburetor studs. 2. Connect breather tube to air cleaner base. If engine has evap air cleaner base, connect evap hose to base. 3. Install air cleaner base onto carburetor studs and secure with nuts.
  • Page 53 18 690 06 Rev. -- KohlerEngines.com...
  • Page 54 KohlerEngines.com 18 690 06 Rev. --...
  • Page 55 18 690 06 Rev. -- KohlerEngines.com...
  • Page 56 1P18 690 06 © 2014 by Kohler Co. All rights reserved. 85612 30913 KohlerEngines.com 18 690 06 Rev. --...

This manual is also suitable for:

Rh265

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