User manual KOHLER CH18-750

SERVICE MANUAL COMMAND CH18-750 HORIZONTAL CRANKSHAFT Contents Section 1. Safety and General Information ............................................................................ 1 2 3 4 5 5A 5B 6 7 8 9 10 11 12 Section 2. Special Tools .......................................................................................................... Section 3. Troubleshooting ..................................................................................................... Section 4. Air Cleaner and Air Intake System ........................................................................ Section 5. Fuel System and Governor .................................................................................... Section 5A. LPG Fuel Systems ............................................................................................... Section 5B. Electronic Fuel Injection (EFI) Fuel System ...................................................... Section 6. Lubrication System ................................................................................................ Section 7. Retractable Starter ................................................................................................. Section 8. Electrical System and Components ..................................................................... Section 9. Disassembly ........................................................................................................... Section 10. Inspection and Reconditioning ........................................................................... Section 11. Reassembly ........................................................................................................... Section 12. Clutch .................................................................................................................... Section 1 Safety and General Information Section 1 Safety and General Information Safety Precautions To ensure safe operation please read the following statements and understand their meaning. Also refer to your equipment manufacturer's manual for other important safety information. This manual contains safety precautions which are explained below. Please read carefully. WARNING Warning is used to indicate the presence of a hazard that can cause severe personal injury, death, or substantial property damage if the warning is ignored. CAUTION Caution is used to indicate the presence of a hazard that will or can cause minor personal injury or property damage if the caution is ignored. NOTE Note is used to notify people of installation, operation, or maintenance information that is important but not hazard-related. For Your Safety! These precautions should be followed at all times. Failure to follow these precautions could result in injury to yourself and others. 1 WARNING WARNING WARNING Accidental Starts can cause severe injury or death. Disconnect and ground spark plug leads before servicing. Rotating Parts can cause severe injury. Stay away while engine is in operation. Hot Parts can cause severe burns. Do not touch engine while operating or just after stopping. Accidental Starts! Disabling engine. Accidental starting can cause severe injury or death. Before working on the engine or equipment, disable the engine as follows: 1) Disconnect the spark plug lead(s). 2) Disconnect negative (-) battery cable from battery. Rotating Parts! Keep hands, feet, hair, and clothing away from all moving parts to prevent injury. Never operate the engine with covers, shrouds, or guards removed. Hot Parts! Engine components can get extremely hot from operation. To prevent severe burns, do not touch these areas while the engine is running - or immediately after it is turned off. Never operate the engine with heat shields or guards removed. 1.1 Section 1 Safety and General Information WARNING WARNING WARNING Explosive Fuel can cause fires and severe burns. Carbon Monoxide can cause severe nausea, fainting or death. Avoid inhaling exhaust fumes, and never run the engine in a closed building or confined area. Explosive Gas can cause fires and severe acid burns. Charge battery only in a well ventilated area. Keep sources of ignition away. Do not fill the fuel tank while the engine is hot or running. Explosive Fuel! Gasoline is extremely flammable and its vapors can explode if ignited. Store gasoline only in approved containers, in well ventilated, unoccupied buildings, away from sparks or flames. Do not fill the fuel tank while the engine is hot or running, since spilled fuel could ignite if it comes in contact with hot parts or sparks from ignition. Do not start the engine near spilled fuel. Never use gasoline as a cleaning agent. Lethal Exhaust Gases! Engine exhaust gases contain poisonous carbon monoxide. Carbon monoxide is odorless, colorless, and can cause death if inhaled. Avoid inhaling exhaust fumes, and never run the engine in a closed building or confined area. Explosive Gas! Batteries produce explosive hydrogen gas while being charged. To prevent a fire or explosion, charge batteries only in well ventilated areas. Keep sparks, open flames, and other sources of ignition away from the battery at all times. Keep batteries out of the reach of children. Remove all jewelry when servicing batteries. Before disconnecting the negative (-) ground cable, make sure all switches are OFF. If ON, a spark will occur at the ground cable terminal which could cause an explosion if hydrogen gas or gasoline vapors are present. WARNING WARNING Uncoiling Spring can cause severe injury. Wear safety goggles or face protection when servicing retractable starter. Cleaning Solvents can cause severe injury or death. Use only in well ventilated areas away from ignition sources. Flammable Solvents! Carburetor cleaners and solvents are extremely flammable. Keep sparks, flames, and other sources of ignition away from the area. Follow the cleaner manufacturer's warnings and instructions on its proper and safe use. Never use gasoline as a cleaning agent. Spring Under Tension! Retractable starters contain a powerful, recoil spring that is under tension. Always wear safety goggles when servicing retractable starters and carefully follow instructions in the "Retractable Starter" Section 7 for relieving spring tension. CAUTION Electrical Shock can cause injury. Do not touch wires while engine is running. Electrical Shock! Never touch electrical wires or components while the engine is running. They can be sources of electrical shock. 1.2 Section 1 Safety and General Information Engine Identification Numbers When ordering parts, or in any communication involving an engine, always give the Model, Specification and Serial Numbers, including letter suffixes if there are any. The engine identification numbers appear on a decal, or decals, affixed to the engine shrouding. See Figure 1-1. An explanation of these numbers is shown in Figure 1-2. 1 Identification Decal Figure 1-1. Engine Identification Decal Location. A. Model No. Command Engine Horizontal Crankshaft Horsepower 17 = 17 HP 18 = 18 HP 20 = 20 HP 22 = 22 HP 23 = 23 HP 25 = 25 HP 26 = 26 HP C H 18 S Version Code S = Electric Start or Numerical Designation 730 740 745 750 B. Spec. No. Engine Model Code Code Model 62 CH18 64 CH20 66 CH22 68 CH25 76 CH22/23 78 CH26 62500 or Variation of Basic Engine (624 cc) (674 cc) CH730-0001 CH740-0001 CH745-0001 CH750-0001 Complete Spec Number (Incorporating Model No. with Variation No. of Basic Spec.) C. Serial No. 3305810334 Year Manufactured Code Factory Code Code Year Code Year 30 2000 21 1991 31 2001 22 1992 32 2002 23 1993 33 2003 24 1994 34 2004 25 1995 35 2005 26 1996 36 2006 27 1997 37 2007 28 1998 29 1999 Figure 1-2. Explanation of Engine Identification Numbers. 1.3 Section 1 Safety and General Information Oil Recommendations Using the proper type and weight of oil in the crankcase is extremely important. So is checking oil daily and changing oil regularly. Failure to use the correct oil, or using dirty oil, causes premature engine wear and failure. Oil Type Use high-quality detergent oil of API (American Petroleum Institute) Service Class SG, SH, SJ or higher. Select the viscosity based on the air temperature at the time of operation as shown in the following table. Refer to Section 6 - "Lubrication System" for detailed procedures on checking the oil, changing the oil and changing the oil filter. Fuel Recommendations WARNING: Explosive Fuel! Gasoline is extremely flammable and its vapors can explode if ignited. Before servicing the fuel system, make sure there are no sparks, open flames or other sources of ignition nearby as these can ignite gasoline vapors. Disconnect and ground the spark plug leads to prevent the possibility of sparks from the ignition system. General Recommendations Purchase gasoline in small quantities and store in clean, approved containers. A container with a capacity of 2 gallons or less with a pouring spout is recommended. Such a container is easier to handle and helps eliminate spillage during refueling. Do not use gasoline left over from the previous season, to minimize gum deposits in your fuel system and to ensure easy starting. Do not add oil to the gasoline. Do not overfill the fuel tank. Leave room for the fuel to expand. Fuel Type For best results, use only clean, fresh, unleaded gasoline with a pump sticker octane rating of 87 or higher. In countries using the Research method, it should be 90 octane minimum. Unleaded gasoline is recommended as it leaves less combustion chamber deposits and reduces harmful exhaust emissions. Leaded gasoline is not recommended and must not be used on EFI engines, or on other models where exhaust emissions are regulated. Gasoline/Alcohol blends Gasohol (up to 10% ethyl alcohol, 90% unleaded gasoline by volume) is approved as a fuel for Kohler engines. Other gasoline/alcohol blends are not approved. Gasoline/Ether blends Methyl Tertiary Butyl Ether (MTBE) and unleaded gasoline blends (up to a maximum of 15% MTBE by volume) are approved as a fuel for Kohler engines. Other gasoline/ether blends are not approved. ** * *Use of synthetic oil having 5W-20 or 5W-30 rating is acceptable, up to 4°C (40°F). **Synthetic oils will provide better starting in extreme cold (below -23°C (-10°F). NOTE: Using other than service class SG, SH, SJ or higher oil or extending oil change intervals longer than recommended can cause engine damage. NOTE: Synthetic oils meeting the listed classifications may be used with oil changes performed at the recommended intervals. However, to allow piston rings to properly seat, a new or rebuilt engine should be operated for at least 50 hours using standard petroleum based oil before switching to synthetic oil. A logo or symbol on oil containers identifies the API service class and SAE viscosity grade. See Figure 1-3. Figure 1-3. Oil Container Logo. 1.4 Section 1 Safety and General Information Periodic Maintenance Instructions WARNING: Accidental Starts! Disabling engine. Accidental starting can cause severe injury or death. Before working on the engine or equipment, disable the engine as follows: 1) Disconnect the spark plug lead(s). 2) Disconnect negative (-) battery cable from battery. Maintenance Schedule These required maintenance procedures should be performed at the frequency stated in the table. They should also be included as part of any seasonal tune-up. Frequency Daily or Before Starting Engine Every 25 Hours Every 100 Hours Maintenance Required · · · · · · · · · · · · Fill fuel tank Check oil level. Check air cleaner for dirty1, loose, or damaged parts. Check air intake and cooling areas, clean as necessary1. Service precleaner element1. Replace air cleaner element1. Change oil. (More frequently under severe conditions.) Remove cooling shrouds and clean cooling areas1,3. Check oil cooler fins, clean as necessary (if equipped). Check spark plug condition and gap. Change oil filter. Change fuel filter (carbureted engines). Refer to: Section 5 Section 6 Section 4 Section 4 Section 4 Section 4 Section 6 Section 4 Section 6 Section 8 Section 6 Section 5 Section 4 Section 8 Section 8 Section 2 Section 5B 1 Every 200 Hours Every 250 Hours Annually or Every 500 Hours Every 500 Hours Every 1500 Hours · Replace heavy-duty air cleaner element and check inner element1. · Have bendix starter drive serviced2. · Have solenoid shift starter disassembled and cleaned2. · Have crankshaft splines lubricated2. · Replace fuel filter1 (EFI engines). ¹Perform these maintenance procedures more frequently under extremely dusty, dirty conditions. ²Only requried for Denso starters. Not necessary on Delco starters. Have a Kohler Engine Service Dealer perform this service. ³Cleanout Kits 25 755 20-S (black) or 25 755 21-S (gold) allow cooling areas to be cleaned without removing shrouds. Storage If the engine will be out of service for two months or more, use the following storage procedure: 1. Clean the exterior surfaces of the engine. On Electronic Fuel Injected (EFI) engines, avoid spraying water at the wiring harness or any of the electrical components. 2. Change the oil and oil filter while the engine is still warm from operation. See "Change Oil and Oil Filter" in Section 6. 3. The fuel system must be completely emptied, or the gasoline must be treated with a stabilizer to prevent deterioration. If you choose to use a stabilizer, follow the manufacturer's recommendations, and add the correct amount for the capacity of the fuel system. Fill the fuel tank with clean, fresh gasoline. Run the engine for 2 to 3 minutes to get stabilized fuel into the rest of the system. Close the fuel shut-off valve when the unit is being stored or transported. To empty the system, run the engine until the tank and the system are empty. 4. Remove the spark plugs and add one tablespoon of engine oil into each spark plug hole. Install the spark plugs, but do not connect the plug leads. Crank the engine two or three revolutions. 5. On equipment with an EFI engine, disconnect the battery or use a battery minder to keep the battery charged during storage. 6. Store the engine in a clean, dry place. 1.5 Section 1 Safety and General Information Dimensions in millimeters. Inch equivalents shown in [ ]. Figure 1-4. Typical Engine Dimensions CH Series with Standard Flat Air Cleaner. 1.6 Section 1 Safety and General Information Dimensions in millimeters. Inch equivalents shown in [ ]. 1 Figure 1-5. Typical Engine Dimensions CH EFI Series with Heavy-Duty Air Cleaner. 1.7 Section 1 Safety and General Information General Specifications¹ Power (@ 3600 RPM, exceeds Society of Automotive Engineers-Small Engine Test Code J1940.) CH18 ........................................................................................................................................ 13.4 kW (18 HP) CH20 ........................................................................................................................................ 14.9 kW (20 HP) CH22 ........................................................................................................................................ 16.4 kW (22 HP) CH23 ........................................................................................................................................ 17.2 kW (23 HP) CH25, CH730 .......................................................................................................................... 18.6 kW (25 HP) CH26 ........................................................................................................................................ 19.4 kW (26 HP) CH740 ...................................................................................................................................... 20.1 kW (27 HP) CH745 ...................................................................................................................................... 20.9 kW (28 HP) CH750 ...................................................................................................................................... 22.3 kW (30 HP) Peak Torque CH18 @ 2200 RPM ................................................................................................................. 43.6 N·m (32.2 ft. lb.) CH20 @ 2400 RPM ................................................................................................................. 44.3 N·m (32.7 ft. lb.) CH22 @ 2400 RPM ................................................................................................................. 49.1 N·m (36.2 ft. lb.) CH23 @ 2400 RPM ................................................................................................................. 54.1 N·m (37.9 ft. lb.) CH25 @ 2200 RPM ................................................................................................................. 54.0 N·m (39.5 ft. lb.) CH730 @ 2400 RPM ............................................................................................................... 55.4 N·m (40.9 ft. lb.) CH26 @ 2800 RPM ................................................................................................................. 54.2 N·m (40.0 ft. lb.) CH740 @ 2400 RPM ............................................................................................................... 57.3 N·m (42.3 ft. lb.) CH745 @ 2600 RPM ............................................................................................................... 57.9 N·m (42.7 ft. lb.) CH750 @ 2400 RPM ............................................................................................................... 64.4 N·m (47.5 ft. lb.) Bore CH18, CH20, CH22 (624 cc) .................................................................................................. 77 mm (3.03 in.) CH22/23 (674 cc) .................................................................................................................... 80 mm (3.15 in.) CH25, CH26, CH730-750 ....................................................................................................... 83 mm (3.27 in.) Stroke CH18-745 ................................................................................................................................ 67 mm (2.64 in.) CH750 ...................................................................................................................................... 69 mm (2.7 in.) Displacement CH18, CH20, CH22 (624 cc) .................................................................................................. 624 cc (38 cu. in.) CH22/23 (674 cc) .................................................................................................................... 674 cc (41 cu. in.) CH25, CH26, CH730-745 ....................................................................................................... 725 cc (44 cu. in.) CH750 ...................................................................................................................................... 755 cc (46 cu. in.) Compression Ratio CH18, CH20, CH22/23 ........................................................................................................... 8.5:1 CH25, CH26, CH730-745 ....................................................................................................... 9.0:1 CH750 ...................................................................................................................................... 9.4:1 Dry Weight CH18, CH20, CH22/23 ........................................................................................................... 41 kg (90 lb.) CH25, CH26, CH730-745 ....................................................................................................... 43 kg (94 lb.) CH750 ...................................................................................................................................... 48 kg (105 lb.) Oil Capacity (w/filter) - approximate, determined by oil filter and oil cooler used ............................................................................. 1.6-1.8 L (1.7-1.9 U.S. qt.) ¹Values are in Metric units. Values in parentheses are English equivalents. Lubricate threads with engine oil prior to assembly. 1.8 Section 1 Safety and General Information General Specifications¹ cont. Angle of Operation - Maximum (At Full Oil Level) All Directions ................... 25° Blower Housing and Sheet Metal M5 Fasteners Torque ................................................................................................ 6.2 N·m (55 in. lb.) into new holes 4.0 N·m (35 in. lb.) into used holes M6 Fasteners Torque ................................................................................................ 10.7 N·m (95 in. lb.) into new holes 7.3 N·m (65 in. lb.) into used holes Rectifier-Regulator Fastener Torque ................................................................... 1.4 N·m (12.6 in. lb.) Camshaft End Play (With Shim) ............................................................................................ 0.076/0.127 mm (0.0030/0.0050 in.) Running Clearance ................................................................................................. 0.025/0.063 mm (0.0010/0.0025 in.) Bore I.D. New .................................................................................................................. 20.000/20.025 mm (0.7874/0.7884 in.) Max. Wear Limit ............................................................................................. 20.038 mm (0.7889 in.) Camshaft Bearing Surface O.D. New .................................................................................................................. 19.962/19.975 mm (0.7859/0.7864 in.) Max. Wear Limit ............................................................................................. 19.959 mm (0.7858 in.) Carburetor and Intake Manifold Intake Manifold Mounting Fastener Torque Torque in Two Stages ..................................................................................... first to 7.4 N·m (66 in. lb.) finally to 9.9 N·m (88 in. lb.) Carburetor Mounting Screw Torque M6 ............................................................ 6.2-7.3 N·m (55-65 in. lb.) Adapter (for Heavy Duty Air Cleaner) Mounting Fastener Torque ................ 7.3 N·m (65 in. lb.) Connecting Rod Cap Fastener Torque (torque in increments) 8 mm straight shank ............................................................................................ 22.7 N·m (200 in. lb.) 8 mm step-down .................................................................................................. 14.7 N·m (130 in. lb.) 6 mm straight shank ............................................................................................ 11.3 N·m (100 in. lb.) Connecting Rod-to-Crankpin Running Clearance New .................................................................................................................. 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. New .................................................................................................................. 17.015/17.023 mm (0.6699/0.6702 in.) Max. Wear Limit ............................................................................................. 17.036 mm (0.6707 in.) ¹Values are in Metric units. Values in parentheses are English equivalents. Lubricate threads with engine oil prior to assembly. 1.9 1 Section 1 Safety and General Information Crankcase Governor Cross Shaft Bore I.D. 6 mm Shaft New .................................................................................................................. 6.025/6.050 mm (0.2372/0.2382 in.) Max. Wear Limit ............................................................................................. 6.063 mm (0.2387 in.) 8 mm Shaft New .................................................................................................................. 8.025/8.075 mm (0.3159/0.3179 in.) Max. Wear Limit ............................................................................................. 8.088 mm (0.3184 in.) Breather Cover Fastener Torque .......................................................................... 7.3 N·m (65 in. lb.) Oil Drain Plug Torque ............................................................................................ 13.6 N·m (10 ft. lb.) Closure Plate Closure Plate Fastener Torque .............................................................................. 24.4 N·m (216 in. lb.) Crankshaft End Play (Free) ........................................................................................................ 0.070/0.590 mm (0.0028/0.0230 in.) End Play (With Thrust Bearing Components) ................................................... 0.070/0.270 mm (0.0028/0.0100 in.) Except CH25 Engines Below Serial No. 2403500008 .......................................... 0.050/0.750 mm (0.0020/0.0295 in.) Crankshaft Bore (In Crankcase) New .................................................................................................................. 40.965/41.003 mm (1.6128/1.6143 in.) Max. Wear Limit ............................................................................................. 41.016 mm (1.6148 in.) Crankshaft to Sleeve Bearing (Crankcase) Running Clearance - New ............................................................................ 0.03/0.09 mm (0.0012/0.0035 in.) Crankshaft Bore (In Closure Plate) - New .......................................................... 40.987/40.974 mm (1.6136/1.6131 in.) Crankshaft Bore (In Closure Plate)-to-Crankshaft Running Clearance - New ............................................................................ 0.039/0.074 mm (0.0015/0.0029 in.) Flywheel End Main Bearing Journal O.D. - New ....................................................................................................... 40.913/40.935 mm (1.6107/1.6116 in.) O.D. - Max. Wear Limit .................................................................................. 40.84 mm (1.608 in.) Max. Taper ....................................................................................................... 0.022 mm (0.0009 in.) Max. Out-of-Round ........................................................................................ 0.025 mm (0.0010 in.) Closure Plate End Main Bearing Journal O.D. - New ....................................................................................................... 40.913/40.935 mm (1.6107/1.6116 in.) O.D. - Max. Wear Limit .................................................................................. 40.84 mm (1.608 in.) Max. Taper ....................................................................................................... 0.022 mm (0.0009 in.) Max. Out-of-Round ........................................................................................ 0.025 mm (0.0010 in.) Connecting Rod Journal O.D. - New ....................................................................................................... 35.955/35.973 mm (1.4156/1.4163 in.) O.D. - Max. Wear Limit .................................................................................. 35.94 mm (1.415 in.) Max. Taper ....................................................................................................... 0.018 mm (0.0007 in.) Max. Out-of-Round ........................................................................................ 0.025 mm (0.0010 in.) 1.10 Section 1 Safety and General Information Crankshaft cont. Crankshaft T.I.R. PTO End, Crank in Engine ............................................................................. 0.279 mm (0.0110 in.) Entire Crank, in V-Blocks .............................................................................. 0.10 mm (0.0039 in.) Cylinder Bore Cylinder Bore I.D. New - CH18, CH20, CH22 (624 cc) ............................................................... 77.000/77.025 mm (3.0315/3.0325 in.) New - CH22/23 (674 cc) ................................................................................. 80.000/80.025 mm (3.1496/3.1506 in.) New - CH25, CH26, CH730-750 ................................................................... 82.988/83.013 mm (3.2672/3.2682 in.) Max. Wear Limit - CH18, CH20, CH22 (624 cc) .......................................... 77.063 mm (3.0340 in.) Max. Wear Limit - CH22/23 (674 cc) ............................................................ 80.065 mm (3.1522 in.) Max. Wear Limit - CH25, CH26, CH730-750 .............................................. 83.051 mm (3.2697 in.) Max. Out-of-Round ........................................................................................ 0.12 mm (0.0047 in.) Max. Taper ....................................................................................................... 0.05 mm (0.0020 in.) Cylinder Head Cylinder Head Fastener Torque Hex Flange Nut - Torque in Two Stages ...................................................... first to 16.9 N·m (150 in. lb.) finally to 33.9 N·m (300 in. lb.) Head Bolt - Torque in Two Stages ................................................................ first to 22.6 N·m (200 in. lb.) finally to 41.8 N·m (370 in. lb.) Max. Out-of-Flatness .............................................................................................. 0.076 mm (0.003 in.) Rocker Arm Screw Torque .................................................................................... 11.3 N·m (100 in. lb.) Fan/Flywheel Fan Fastener Torque ............................................................................................... 9.9 N·m (88 in. lb.) Flywheel Retaining Screw Torque ....................................................................... 66.4 N·m (49 ft. lb.) Governor Governor Cross Shaft-to-Crankcase Running Clearance 6 mm Shaft ............................................................................................................. 0.013/0.075 mm (0.0005/0.0030 in.) 8 mm Shaft ............................................................................................................. 0.025/0.126 mm (0.0009/0.0049 in.) Governor Cross Shaft O.D. 6 mm Shaft New .................................................................................................................. Max. Wear Limit ............................................................................................. 8 mm Shaft New .................................................................................................................. Max. Wear Limit ............................................................................................. 1 5.975/6.012 mm (0.2352/0.2367 in.) 5.962 mm (0.2347 in.) 7.949/8.000 mm (0.3129/0.3149 in.) 7.936 mm (0.3124 in.) Governor Gear Shaft-to-Governor Gear Running Clearance ......................... 0.015/0.140 mm (0.0006/0.0055 in.) Governor Gear Shaft O.D. New .................................................................................................................. 5.990/6.000 mm (0.2358/0.2362 in.) Max. Wear Limit ............................................................................................. 5.977 mm (0.2353 in.) Governor Lever Nut Torque ................................................................................. 6.8 N·m (60 in. lb.) 1.11 Section 1 Safety and General Information Ignition Spark Plug Type (Champion® or Equivalent) ..................................................... RC12YC, XC12YC, or Platinum 3071 Spark Plug Gap ....................................................................................................... 0.76 mm (0.030 in.) Spark Plug Torque .................................................................................................. 24.4-29.8 N·m (18-22 ft. lb.) Ignition Module Air Gap ....................................................................................... 0.28/0.33 mm (0.011/0.013 in.) Ignition Module Fastener Torque ......................................................................... 4.0-6.2 N·m (35-55 in. lb.) Speed Sensor Air Gap (EFI engines) ..................................................................... 1.50 ± 0.25 mm (0.059 ± 0.010 in.) Muffler Muffler Retaining Nut Torque .............................................................................. 24.4 N·m (216 in. lb.) Oil Filter Oil Filter Torque ...................................................................................................... 3/4-1 turn after gasket contact Oil Cooler Oil Cooler/Adapter Nipple Torque ...................................................................... 27 N·m (20 ft. lb.) Piston, Piston Rings, and Piston Pin Piston-to-Piston Pin Running Clearance ............................................................ 0.006/0.017 mm (0.0002/0.0007 in.) Piston Pin Bore I.D. New .................................................................................................................. 17.006/17.012 mm (0.6695/0.6698 in.) Max. Wear Limit ............................................................................................. 17.025 mm (0.6703 in.) Piston Pin O.D. New .................................................................................................................. 16.995/17.000 mm (0.6691/0.6693 in.) Max. Wear Limit ............................................................................................. 16.994 mm (0.6691 in.) Top Compression Ring-to-Groove Side Clearance CH18, CH20, CH22 (624 cc) ........................................................................... 0.040/0.080 mm (0.0016/0.0031 in.) CH22/23 (674 cc) ............................................................................................. 0.030/0.076 mm (0.0012/0.0030 in.) CH25, CH26, CH730-750 ............................................................................... 0.025/0.048 mm (0.0010/0.0019 in.) Middle Compression Ring-to-Groove Side Clearance CH18, CH20, CH22 (624 cc) ........................................................................... 0.040/0.080 mm (0.0016/0.0031 in.) CH22/23 (674 cc) ............................................................................................. 0.030/0.076 mm (0.0012/0.0030 in.) CH25, CH26, CH730-750 ............................................................................... 0.015/0.037 mm (0.0006/0.0015 in.) Oil Control Ring-to-Groove Side Clearance CH18, CH20, CH22 (624 cc) ........................................................................... 0.060/0.202 mm (0.0024/0.0080 in.) CH22/23 (674 cc) ............................................................................................. 0.046/0.196 mm (0.0018/0.0077 in.) CH25, CH26, CH730-750 ............................................................................... 0.026/0.176 mm (0.0010/0.0070 in.) 1.12 Section 1 Safety and General Information Piston, Piston Rings, and Piston Pin cont. Top and Center Compression Ring End Gap New Bore - CH18, CH20, CH22 (624 cc) ...................................................... 0.25/0.45 mm (0.0098/0.0177 in.) New Bore - CH22/23 (674 cc) ........................................................................ 0.18/0.46 mm (0.0071/0.0181 in.) New Bore - CH25, CH26, CH730-745 .......................................................... 0.25/0.56 mm (0.0100/0.0224 in.) Used Bore (Max.) - CH18, CH20, CH22 (624 cc) .......................................... 0.77 mm (0.030 in.) Used Bore (Max.) - CH22/23 (674 cc) ............................................................ 0.80 mm (0.0315 in.) Used Bore (Max.) - CH25, CH26, CH730-750 .............................................. 0.94 mm (0.037 in.) Piston Thrust Face O.D.² New - CH18, CH20, CH22 (624 cc) ............................................................... 76.967/76.985 mm (3.0302/3.0309 in.) New - CH22/23 (674 cc) ................................................................................. 79.963/79.979 mm (3.1481/3.1488 in.) New - CH25, CH26, CH730-750 ................................................................... 82.986 mm (3.2671 in.) Max. Wear Limit - CH18, CH20, CH22 (624 cc) .......................................... 76.840 mm (3.0252 in.) Max. Wear Limit - CH22 (674 cc) ................................................................. 79.831 mm (3.1430 in.) Max. Wear Limit - CH25, CH26, CH730-750 .............................................. 82.841 mm (3.2614 in.) Piston Thrust Face-to-Cylinder Bore² Running Clearance New - CH18, CH20, CH22 (624 cc) ............................................................... 0.014/0.057 mm (0.0005/0.0022 in.) New - CH22/23 (674 cc) ................................................................................. 0.021/0.062 mm (0.0008/0.0024 in.) New - CH25, CH26, CH730-750 ................................................................... 0.001/0.045 mm (0.039/0.0018 in.) Speed Control Bracket Fastener Torque ....................................................................................................... 10.7 N·m (95 in. lb.) into new holes 7.3 N·m (65 in. lb.) into used holes Starter Assembly Thru Bolt Torque UTE/Johnson Electric, Eaton (Inertia Drive) ............................................... 4.5-5.7 N·m (40-50 in. lb.) Nippondenso (Solenoid Shift) ...................................................................... 4.5-7.5 N·m (40-84 in. lb.) Delco-Remy (Solenoid Shift) ......................................................................... 5.6-9.0 N·m (49-79 in. lb.) Mounting Screw Torque (All) ............................................................................... 15.3 N·m (135 in. lb.) Brush Holder Mounting Screw Torque Delco-Remy Starter ........................................................................................ 2.5-3.3 N·m (22-29 in. lb.) Solenoid (Starter) Mounting Hardware Torque 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 Torque Nippondenso Starter ..................................................................................... 8.0-12.0 N·m (71-106 in. lb.) Delco-Remy Starter ........................................................................................ 8.0-11.0 N·m (71-97 in. lb.) Stator Mounting Screw Torque ........................................................................................ 6.2 N·m (55 in. lb.) 1 ²Measure 6 mm (0.236 in.) above the bottom of the piston skirt at right angles to the piston pin. 1.13 Section 1 Safety and General Information Valve Cover Valve Cover Fastener Torque Gasket Style Cover ................................................................................................. 3.4 N·m (30 in. lb.) Black O-Ring Style Cover w/Shoulder Screws ........................................................................................ 5.6 N·m (50 in. lb.) w/Flange Screws and Spacers ...................................................................... 9.9 N·m (88 in. lb.) Yellow or Brown O-Ring Style Cover w/Integral Metal Spacers .................... 6.2 N·m (55 in. lb.) Valves and Valve Lifters Hydraulic Valve Lifter to Crankcase Running Clearance ................................ 0.0241/0.0501 mm (0.0009/0.0020 in.) Intake Valve Stem-to-Valve Guide Running Clearance ................................... 0.038/0.076 mm (0.0015/0.0030 in.) Exhaust Valve Stem-to-Valve Guide Running Clearance ................................ 0.050/0.088 mm (0.0020/0.0035 in.) Intake Valve Guide I.D. New .................................................................................................................. 7.038/7.058 mm (0.2771/0.2779 in.) Max. Wear Limit ............................................................................................. 7.134 mm (0.2809 in.) Exhaust Valve Guide I.D. New .................................................................................................................. 7.038/7.058 mm (0.2771/0.2779 in.) Max. Wear Limit ............................................................................................. 7.159 mm (0.2819 in.) Valve Guide Reamer Size Standard .......................................................................................................... 7.048 mm (0.2775 in.) 0.25 mm O.S. .................................................................................................... 7.298 mm (0.2873 in.) Intake Valve Minimum Lift ................................................................................... 8.07 mm (0.3177 in.) Exhaust Valve Minimum Lift ............................................................................... 8.07 mm (0.3177 in.) Nominal Valve Seat Angle .................................................................................... 45° 1.14 Section 1 Safety and General Information General Torque Values Metric Fastener Torque Recommendations for Standard Applications 1 Tightening Torque: N·m (in. lb.) + or - 10% Property Class Noncritical Fasteners Into Aluminum 10.9 12.9 4.8 Size M4 M5 M6 M8 1.2 (11) 2.5 (22) 4.3 (38) 10.5 (93) 5.8 8.8 1.7 (15) 3.2 (28) 5.7 (50) 13.6 (120) 2.9 (26) 5.8 (51) 9.9 (88) 24.4 (216) 4.1 (36) 8.1 (72) 14.0 (124) 33.9 (300) 5.0 (44) 9.7 (86) 16.5 (146) 40.7 (360) 2.0 (18) 4.0 (35) 6.8 (60) 17.0 (150) Tightening Torque: N·m (ft. lb.) + or - 10% Property Class Noncritical Fasteners Into Aluminum 10.9 12.9 4.8 5.8 8.8 M10 M12 M14 21.7 (16) 36.6 (27) 58.3 (43) 27.1 (20) 47.5 (35) 76.4 (55) 47.5 (35) 82.7 (61) 131.5 (97) 66.4 (49) 116.6 (86) 184.4 (136) 81.4 (60) 139.7 (103) 219.7 (162) 33.9 (25) 61.0 (45) 94.9 (70) 1.15 Section 1 Safety and General Information English Fastener Torque Recommendations for Standard Applications Tightening Torque: N·m (in. lb.) + or - 20% Bolts, Screws, Nuts and Fasteners Assembled Into Cast Iron or Steel Grade 2 or 5 Fasteners Into Aluminum Grade 2 Size 8-32 10-24 10-32 1/4-20 1/4-28 5/16-18 5/16-24 3/8-16 3/8-24 2.3 (20) 3.6 (32) 3.6 (32) 7.9 (70) 9.6 (85) 17.0 (150) 18.7 (165) 29.4 (260) 33.9 (300) Grade 5 2.8 (25) 4.5 (40) 4.5 (40) 13.0 (115) 15.8 (140) 28.3 (250) 30.5 (270) ----------------- Grade 8 ------------------------18.7 (165) 22.6 (200) 39.6 (350) ------------------------2.3 (20) 3.6 (32) --------7.9 (70) --------17.0 (150) ------------------------- Tightening Torque: N·m (ft. lb.) + or - 20% Size 5/16-24 3/8-16 3/8-24 7/16-14 7/16-20 1/2-13 1/2-20 9/16-12 9/16-18 5/8-11 5/8-18 3/4-10 3/4-16 ------------------------47.5 (35) 61.0 (45) 67.8 (50) 94.9 (70) 101.7 (75) 135.6 (100) 149.2 (110) 189.8 (140) 199.3 (150) 271.2 (200) ---------47.5 (35) 54.2 (40) 74.6 (55) 101.7 (75) 108.5 (80) 142.4 (105) 169.5 (125) 223.7 (165) 244.1 (180) 311.9 (230) 332.2 (245) 440.7 (325) 40.7 (30) 67.8 (50) 81.4 (60) 108.5 (80) 142.4 (105) 155.9 (115) 223.7 (165) 237.3 (175) 311.9 (230) 352.6 (260) 447.5 (330) 474.6 (350) 637.3 (470) --------------------------------------------------------------------------------------------------------- Torque Conversions N·m = in. lb. x 0.113 N·m = ft. lb. x 1.356 in. lb. = N·m x 8.85 ft. lb. = N·m x 0.737 1.16 Section 2 Tools & Aids Section 2 Tools & Aids Certain quality tools are designed to help you perform specific disassembly, repair, and reassembly procedures. By using tools designed for the job, 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 the list of tools and their source. Separate Tool Suppliers: Kohler Tools Contact your 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 2 Tools Description Balance Gear Tim ing Tool (K & M Ser ies) To hold balance gears in timed position when assembling engine. Cam shaft Endplay Plat e For checking camshaft endplay. Cylinder Leakdow n Test er For checking combustion retention and if cylinder, piston, rings, or valves are worn. Elect r onic Fuel Inject ion (EFI) Diagnost ic Soft w ar e U se with Laptop or Desktop PC. EFI Ser vice Kit For troubleshooting and setting up an EFI engine. Individual Components Available Pressure Tester Noid Light 90° Adapter Oetiker Clamp Pliers Code Plug, Red Wire Code Plug, Blue Wire Flyw heel Holding Tool (CS Ser ies) Flyw heel Puller To remove flywheel from engine. Source/Part No. Kohler 25 455 06-S (Formerly Y-357) S E Tools KLR-82405 Kohler 25 761 05-S Kohler 25 761 23-S Kohler 24 761 01-S Design Technology Inc. DTI-019 DTI-021 DTI-023 DTI-025 DTI-027 DTI-029 S E Tools KLR-82407 S E Tools KLR-82408 2.1 Section 2 Tools & Aids Tools (cont.) Description Flyw heel St r ap Wr ench To hold flywheel during removal. Hydr aulic Valve Lift er Tool To remove and install hydraulic lifters. Ignit ion Syst em Test er For testing output on all systems, except CD. For testing output on capacitive discharge (CD) ignition system. Offset Wr ench (K & M Ser ies) To remove and reinstall cylinder barrel retaining nuts. Oil Pr essur e Test Kit To test and verify oil pressure. Rect ifier -Regulat or Test er (120 volt cur r ent ) Rect ifier -Regulat or Test er (240 volt cur r ent ) U sed to test rectifier-regulators. Individual Components Available CS -PRO Regulator Test Harness S pecial Regulator Test Harness with Diode Spar k Advance Module (SAM) Test er To test the S AM (AS AM and DS AM) on engines with S MART-S PARKTM. St ar t er Br ush Holding Tool (Solenoid Shift ) To hold brushes during servicing. St ar t er Ret aining Ring Tool (Iner t ia Dr ive) To remove and reinstall drive retaining rings (excluding FAS CO starters). St ar t er Ser vicing Kit (All St ar t er s) To remove and reinstall drive retaining rings and brushes. Individual Component Available S tarter Brush Holding Tool (S olenoid S hift) Tachom et er (Digit al Induct ive) For checking operating speed (RPM) of an engine. Vacuum /Pr essur e Test er Alternative to a water manometer. Valve Guide Ream er (K & M Ser ies) For sizing valve guides after installation. Valve Guide Ser vice Kit (Cour age, Aegis, Com m and, OHC) For servicing worn value guides. Source/Part No. S E Tools KLR-82409 Kohler 25 761 38-S Kohler 25 455 01-S Kohler 24 455 02-S S E Tools KLR-82410 Kohler 25 761 06-S Kohler 25 761 20-S Kohler 25 761 41-S Design Technology Inc. DTI-031 DTI-033 Kohler 25 761 40-S S E Tools KLR-82416 Kohler 25 761 18-S S E Tools KLR-82411 S E Tools KLR-82416 Design Technology Inc. DTI-110 Kohler 25 761 22-S S E Tools KLR-82413 S E Tools KLR-82415 2.2 Section 2 Tools & Aids Aids Description Cam shaft Lubr icant (Valspar ZZ613) Dielect r ic Gr ease (GE/Novaguard G661) Dielect r ic Gr ease (Fel-Pro) Elect r ic St ar t er Dr ive Lubr icant (Inertia Drive) Elect r ic St ar t er Dr ive Lubr icant (S olenoid S hift) 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. Loctite® Nos. 5900 or 5910 are recommended for best sealing characteristics. Loctite® Loctite® Loctite® Loctite® 5910 U ltra Black 598 U ltra Blue 587 U ltra Copper Kohler 25 357 12-S Source/Part No. Kohler 25 357 14-S Kohler 25 357 11-S Lubri-S el Kohler 52 357 01-S Kohler 52 357 02-S Kohler 25 597 07-S 2 Spline Dr ive Lubr icant 2.3 Section 2 Tools & Aids Special Tools You Can Make Flywheel Holding Tool A flywheel holding tool can be made out of an old junk flywheel ring gear as shown in Figure 2-1, and used in place of a strap wrench. 1. Using an abrasive cut-off wheel, cut out a six tooth segment of the ring gear as shown. 2. Grind off any burrs or sharp edges. 3. Invert the segment and place it between the ignition bosses on the crankcase so that the tool teeth engage the flywheel ring gear teeth. The bosses will lock the tool and flywheel in position for loosening, tightening or removing with a puller. 2. Remove the studs of a Posi-Lock rod or grind off the aligning steps of a Command rod, so the joint surface is flat. 3. Find a 1 in. long capscrew with the correct thread size to match the threads in the connecting rod. 4. Use a flat washer with the correct I.D. to slip on the capscrew and approximately 1" O.D. (Kohler Part No. 12 468 05-S). Assemble the capscrew and washer to the joint surface of the rod, as shown in Figure 2-2. Figure 2-2. Rocker Arm/Crankshaft Tool. Figure 2-1. Flywheel Holding Tool. Rocker Arm/Crankshaft Tool A spanner wrench to lift the rocker arms or turn the 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 the rod cap. 2.4 Section 3 Troubleshooting Section 3 Troubleshooting Troubleshooting Guide When troubles occur, be sure to check the simple causes which, at first, 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. Use these to locate the causing factors. Refer to the specific section(s) within this service manual for more detailed information. Engine Cranks But Will Not Start 1. Empty fuel tank. 2. Fuel shut-off valve closed. 3. Poor fuel, dirt or water in the fuel system. 4. Clogged fuel line. 5. Spark plug lead(s) disconnected. 6. Key switch or kill switch in "off" position. 7. Faulty spark plugs. 8. Faulty ignition module(s). 9. SMART-SPARKTM malfunction (applicable models). 10. Carburetor solenoid malfunction. 11. Diode in wiring harness failed in open circuit mode. 12. Vacuum fuel pump malfunction, or oil in vacuum hose. 13. Vacuum hose to fuel pump leaking/cracked. 14. Battery connected backwards. 15. Safety interlock system engaged. Engine Starts But Does Not Keep Running 1. Restricted fuel tank cap vent. 2. Poor fuel, dirt or water in the fuel system. 3. Faulty or misadjusted choke or throttle controls. 4. Loose wires or connections that short the kill terminal of ignition module to ground. 5. Faulty cylinder head gasket. 6. Faulty carburetor. 7. Vacuum fuel pump malfunction, or oil in vacuum hose. 8. Leaking/cracked vacuum hose to fuel pump. 9. Intake system leak. 10. Diode in wiring harness failed in open circuit mode. Engine Starts Hard 1. PTO drive is engaged. 2. Dirt or water in the fuel system. 3. Clogged fuel line. 4. Loose or faulty wires or connections. 5. Faulty or misadjusted choke or throttle controls. 6. Faulty spark plugs. 7. Low compression. 8. Weak spark. 9. Fuel pump malfunction causing lack of fuel. 10. Engine overheated-cooling/air circulation restricted. 11. Quality of fuel. 12. Flywheel key sheared. 13. Intake system leak. Engine Will Not Crank 1. PTO drive is engaged. 2. Battery is discharged. 3. Safety interlock switch is engaged. 4. Loose or faulty wires or connections. 5. Faulty key switch or ignition switch. 6. Faulty electric starter or solenoid. 7. Seized internal engine components. Engine Runs But Misses 1. Dirt or water in the fuel system. 2. Spark plug lead disconnected. 3. Poor quality of fuel. 4. Faulty spark plug(s). 5. Loose wires or connections that intermittently ground the ignition kill circuit. 6. Engine overheated. 7. Faulty ignition module or incorrect air gap. 8. Carburetor adjusted incorrectly. 9. SMART-SPARKTM malfunction (applicable models). 3 3.1 Section 3 Troubleshooting Engine Will Not Idle 1. Dirt or water in the fuel system. 2. Stale fuel and/or gum in carburetor. 3. Faulty spark plugs. 4. Fuel supply inadequate. 5. Idle speed adjusting screw improperly set. 6. Idle fuel adjusting needle improperly set (some models). 7. Low compression. 8. Restricted fuel tank cap vent. 9. Engine overheated-cooling system/air circulation problem. Engine Overheats 1. Air intake/grass screen, cooling fins, or cooling shrouds clogged. 2. Excessive engine load. 3. Low crankcase oil level. 4. High crankcase oil level. 5. Faulty carburetor. 6. Lean fuel mixture. 7. SMART-SPARKTM malfunction (applicable models). Engine Knocks 1. Excessive engine load. 2. Low crankcase oil level. 3. Old or improper fuel. 4. Internal wear or damage. 5. Hydraulic lifter malfunction. 6. Quality of fuel. 7. Incorrect grade of oil. Engine Loses Power 1. Low crankcase oil level. 2. High crankcase oil level. 3. Dirty air cleaner element. 4. Dirt or water in the fuel system. 5. Excessive engine load. 6. Engine overheated. 7. Faulty spark plugs. 8. Low compression. 9. Exhaust restriction. 10. SMART-SPARKTM malfunction (applicable models). 11. Low battery. 12. Incorrect governor setting. Engine Uses Excessive Amount of Oil 1. Incorrect oil viscosity/type. 2. Clogged or improperly assembled breather. 3. Breather reed broken. 4. Worn or broken piston rings. 5. Worn cylinder bore. 6. Worn valve stems/valve guides. 7. Crankcase overfilled. 8. Blown head gasket/overheated. Oil Leaks from Oil Seals, Gaskets 1. Crankcase breather is clogged or inoperative. 2. Breather reed broken. 3. Loose or improperly torqued fasteners. 4. Piston blowby or leaky valves. 5. Restricted exhaust. External Engine Inspection Before cleaning or disassembling the engine, make a thorough inspection of its external appearance and condition. This inspection can give clues to what might be found inside the engine (and the cause) when it is disassembled. · Check for buildup of dirt and debris on the crankcase, cooling fins, grass screen, and other external surfaces. Dirt or debris on these areas are causes of higher operating temperatures and overheating. · Check for obvious fuel and oil leaks, and damaged components. Excessive oil leakage can indicate a clogged or improperly-assembled breather, worn/damaged seals and gaskets, or loose or improperly-torqued fasteners. · Check the air cleaner cover and base for damage or indications of improper fit and seal. · Check the air cleaner element. Look for holes, tears, cracked or damaged sealing surfaces, or other damage that could allow unfiltered air into the engine. Also note if the element is dirty or clogged. These could indicate that the engine has been under serviced. · Check the carburetor throat for dirt. Dirt in the throat is further indication that the air cleaner is not functioning properly. · Check the oil level. Note if the oil level is within the operating range on the dipstick, or if it is low or overfilled. 3.2 Section 3 Troubleshooting · Check the condition of the oil. Drain the oil into a container - the oil should flow 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 overrich carburetion, weak ignition, overextended oil change interval or wrong weight or type of oil was used, to name a few. NOTE: It is good practice to drain oil at a location away from the workbench. Be sure to allow ample time for complete drainage. To test the crankcase vacuum with the manometer: 1. Insert the stopper/hose into the oil fill hole. Leave the other tube of manometer open to atmosphere. Make sure the shut off clamp is closed. 2. Start the engine and run at no-load high speed (3200 to 3750 RPM). 3. Open the clamp and note the water level in the tube. The level in the engine side should be a minimum of 10.2 cm (4 in.) above the level in the open side. If the level in the engine side is less than specified (low/no vacuum), or the level in the engine side is lower than the level in the open side (pressure), check for the conditions in the table on page 3.4. 4. Close the shut off clamp before stopping the engine. To test the crankcase vacuum with the Vacuum/ Pressure Gauge Kit (see Section 2): 1. Remove the dipstick or oil fill plug/cap. 2. Install the adapter into the oil fill/dipstick tube opening, upside down over the end of a small diameter dipstick tube, or directly into engine if a tube is not used. 3. Push the barbed fitting on the gauge solidly into the hole in the adapter. 4. Start the engine and bring it up to operating speed (3200-3600 RPM). 5. Check the reading on the gauge. If the reading is to the left of "0" on the gauge, vacuum or negative pressure is indicated. If the reading is to the right of "0" on the gauge, positive pressure is present. Crankcase vacuum should be 4-10 (inches of water) If the reading is below specification, or if pressure is present, check the following table for possible causes and remedies. 3 Cleaning the Engine After inspecting the external condition of the engine, clean the engine thoroughly before disassembling it. Also clean individual components as the 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 the manufacturer's instructions and safety precautions carefully. Make sure all traces of the cleaner are removed before the engine is reassembled and placed into operation. Even small amounts of these cleaners can quickly break down the lubricating properties of engine oil. Basic Engine Tests Crankcase Vacuum Test A partial vacuum should be present in the crankcase when the engine is operating. Pressure in the 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 (see Section 2). Complete instructions are provided in the kits. 3.3 Section 3 Troubleshooting No Crankcase Vacuum/Pressure in Crankcase Possible Cause 1. Crankcase breather clogged or inoperative. Solution 1. Disassemble breather, clean parts thoroughly, check sealing surfaces for flatness, reassemble, and recheck pressure. 2. Replace all worn or damaged seals and gaskets. Make sure all fasteners are tightened securely. Use appropriate torque values and sequences when necessary. 3. Recondition piston, rings, cylinder bore, valves, and valve guides. 4. Repair/replace restricted muffler/exhaust system. If the flywheel end is more accessible, use a breaker bar and socket on the flywheel nut/ screw to hold it in position. An assistant may be needed to hold the breaker bar during testing. If the 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 that the engine cannot rotate off of TDC in either direction. 4. Install the adapter into the spark plug hole, but do not attach it to the tester at this time. 5. Connect an air source of at least 50 psi to the tester. 6. Turn the regulator knob in the increase (clockwise) direction until the gauge needle is in the yellow "set" area at the low end of the scale. 7. Connect the tester quick-disconnect to the adapter hose while firmly holding the engine at TDC. Note the gauge reading and listen for escaping air at the carburetor intake, exhaust outlet, and crankcase breather. 8. Check your test results against the following table: 2. Seals and/or gaskets leaking. Loose or improperly torqued fasteners. 3. Piston blowby or leaky valves (confirm by inspecting components). 4. Restricted exhaust. Compression Test Some of these engines are equipped with an automatic compression release (ACR) mechanism. Because of the ACR mechanism, it is difficult to obtain an accurate compression reading. As an alternative, perform a cylinder leakdown test. Cylinder Leakdown Test A cylinder leakdown test can be a valuable alternative to a compression test. By pressurizing the combustion chamber from an external air source you can determine if the valves or rings are leaking, and how badly. Cylinder Leakdown Tester (see Section 2) is a relatively simple, inexpensive leakdown tester for small engines. The tester includes a quick disconnect for attaching the adapter hose, and a holding tool. Leakdown Test Instructions 1. Run engine for 3-5 minutes to warm it up. 2. Remove spark plug(s) and air filter from engine. 3. Rotate the crankshaft until the piston (of cylinder being tested) is at top dead center of the compression stroke. Hold the engine in this position while testing. The holding tool supplied with the tester can be used if the PTO end of the crankshaft is accessible. Lock the holding tool onto the crankshaft. Install a 3/8" breaker bar into the hole/slot of the holding tool, so it is perpendicular to both the holding tool and crankshaft PTO. 3.4 Section 3 Troubleshooting Leakdown Test Results Air escaping from crankcase breather ........................................................ Defective rings or worn cylinder. Air escaping from exhaust system .............................................................. Defective exhaust valve/improper seating. Air escaping from carburetor ....................................................................... Defective intake valve/improper seating. Gauge reading in "low" (green) zone .......................................................... Piston rings and cylinder in good condition. Gauge reading in "moderate" (yellow) zone .............................................. Engine is still usable, but there is some wear present. Customer should start planning for overhaul or replacement. Gauge reading in "high" (red) zone ............................................................. Rings and/or cylinder have considerable wear. Engine should be reconditioned or replaced. 3 3.5 Section 4 Air Cleaner and Air Intake System Air Cleaners General Most engines are equipped with a replaceable, highdensity paper air cleaner element, surrounded by an oiled foam precleaner, and housed under a flat outer cover. This is typically referred to as the standard air cleaner assembly. See Figures 4-1 and 4-4. Some engines utilize a heavy-duty style air cleaner as shown in Figure 4-12. 4 Figure 4-2. Removing Latch Style Cover. Cover Air Cleaner Element Figure 4-1. Standard Air Cleaner. Precleaner Standard Air Cleaner Service Check the air cleaner daily or before starting the engine. Check for and correct any buildup of dirt and debris, along with loose or damaged components. NOTE: Operating the engine with loose or damaged air cleaner components could allow unfiltered air into the engine, causing premature wear and failure. Figure 4-3. Removing Knob Style Cover. Precleaner Service If so equipped, wash and reoil the precleaner every 25 hours of operation (more often under extremely dusty or dirty conditions). To service the precleaner, perform the following steps: 1. Unhook the latches or loosen the retaining knob, and remove the cover. 2. Remove the foam precleaner from the paper air cleaner element. 4.1 Section 4 Air Cleaner and Air Intake System 3. Wash the precleaner in warm water with detergent. Rinse the precleaner thoroughly until all traces of detergent are eliminated. Squeeze out excess water (do not wring). Allow the precleaner to air dry. 4. Saturate the precleaner with new engine oil. Squeeze out all excess oil. 5. Reinstall the precleaner over the paper air cleaner element. 6. Reinstall the air cleaner cover. Secure the cover with the two latches or the retaining knob. Element Cover Wing Nut Precleaner Seal Figure 4-6. Removing Elements. Element Figure 4-4. Air Cleaner Components. Figure 4-7. Removing Rubber Seal from Bracket. Paper Element Service (Standard Type) Every 100 hours of operation (more often under extremely dusty or dirty conditions), replace the paper element. Follow these steps: 1. Unhook the latches or loosen the retaining knob, and remove the cover. 2. Remove the wing nut, element cover, and paper element with precleaner (if so equipped). 3. Remove the precleaner (if so equipped) from the paper element. Service the precleaner as described in "Precleaner Service". 4. Do not wash the paper element or use pressurized air, as this will damage the element. Replace a dirty, bent, or damaged element with a genuine Kohler element. Handle new elements carefully; do not use if the sealing surfaces are bent or damaged. Figure 4-5. Removing Element Cover Wing Nut. 4.2 Section 4 Air Cleaner and Air Intake System 5. Check the seal for any damage or deterioration. Replace as necessary. See Figure 4-7. 6. Reinstall the seal, paper element, precleaner, element cover, and wing nut. 7. Reinstall the air cleaner cover and secure with the latches or the retaining knob. NOTE: Make sure the correct depth air cleaner element and rubber seal are used for the engine spec involved. Some engines use a deeper or extra capacity air cleaner and a longer rubber seal. 4 Figure 4-8. Exploded View of Standard Air Intake System Components. 4.3 Section 4 Air Cleaner and Air Intake System Air Cleaner Element Cover and Seal - Make sure element cover is not bent or damaged. Make sure the wing nut and seal are in place to ensure the element is sealed against leakage. Air Cleaner Base - Make sure the base is secured tightly to the carburetor and not cracked or damaged. Breather Tube - Make sure the tube is attached to both the air cleaner base and the breather cover. NOTE: Damaged, worn or loose air cleaner components can allow unfiltered air into the engine causing premature wear and failure. Tighten or replace all loose or damaged components. Figure 4-9. Bracket Retaining Screw. Rear Mounting Screws Complete Disassembly and Reassembly Standard Type If the base plate on the standard type has to be removed, proceed as follows: 1. Remove air cleaner components as described earlier. 2. Remove the hex flange screws securing the bracket and base. See Figures 4-9 and 4-10. Remove the bracket. Figure 4-10. Rear Mounting Screws (Used with Plastic Intake Manifold). 3. Pinch the sealing collar on the breather hose and push it down through the hole in the air cleaner base. Carefully feed the upper section of the breather tube down through the base. See Figure 4-11. 4. Remove the base and gasket. 5. Reverse the procedure to reinstall new or serviced components. Torque screws to 9.9 N·m (88 in. lb.). Heavy-Duty Air Cleaner General The heavy-duty air cleaner consists of a cylindrical housing, typically mounted to a bracket off the upper valve cover screws, and connected with a formed rubber hose to an adapter on the carburetor or throttle body/intake manifold (EFI units). The air cleaner housing contains a paper element and inner element, designed for longer service intervals. The system is CARB/EPA certified and the components should not be altered or modified in any way. Figure 4-11. Breather Tube. Air Cleaner Components Whenever the air cleaner cover is removed, or the paper element or precleaner are serviced, check the following: 4.4 Section 4 Air Cleaner and Air Intake System 4. Do not wash the paper element and inner element or use compressed air, this will damage the elements. Replace dirty, bent or damaged elements with new genuine Kohler elements as required. Handle the new elements carefully; do not use if the sealing surfaces are bent or damaged. 5. Check all parts for wear, cracks, or damage. Replace any damaged components. 6. Install the new inner element, followed by the outer element. Slide each fully into place in the air cleaner housing. 7. Reinstall the end cap so the dust ejector valve is down, and secure with the two retaining clips. See Figure 4-12. Removal 1. Remove the upper valve cover screws on each side, securing the main bracket, and loosen the hose clamp on the adapter inlet, or remove the adapter mounting screws. 2. Lift the entire air cleaner assembly off the engine. Disassemble or service as required. Installation 1. Install the main mounting bracket with the center section up and the cutout around the carburetor, aligning the mounting holes with the four upper valve cover holes. 2. Install and torque the four valve cover mounting screws to specified torque value. 3. Reconnect the hose to the adapter and tighten the clamp, or install a new adapter gasket (if the adapter was separated from the carburetor), and torque the mounting fasteners to 7.3 N·m (65 in. lb.). NOTE: Adapter configurations may vary depending on engine and application involved. Two adapters are shown in Figure 4-14. Figure 4-12. Heavy-Duty Air Cleaner. To Service Every 250 hours of operation (more often under extremely dusty or dirty conditions), replace the paper element and check the inner element. Follow these steps. 1. Unhook the two retaining clips and remove the end cap from the air cleaner housing. 2. Pull the air cleaner element out of the housing. See Figure 4-13. 4 Element Inner Element Figure 4-13. Removing Elements. 3. After the element is removed, check the condition of the inner element. It should be replaced whenever it appears dirty, typically every other time the main element is replaced. Clean the area around the base of the inner element before removing it, so dirt does not get into the engine. 4.5 Section 4 Air Cleaner and Air Intake System *Cleanout kits, Kohler Part No. 25 755 20-S (black) or 25 755 21-S (gold), are recommended to aid inspection and cleanout of the cooling fins. See Figure 4-15. NOTE: Operating the engine with a blocked grass screen, dirty or plugged cooling fins, and/or cooling shrouds removed, will cause engine damage due to overheating. Figure 4-14. Adapters for Heavy-Duty Air Cleaners. Air Intake/Cooling System To ensure proper cooling, make sure the grass screen, cooling fan fins, and external surfaces of the engine are kept clean at all times. Every 100 hours of operation (more often under extremely dusty or dirty conditions), remove the blower housing and other cooling shrouds. *Clean the cooling fins and external surfaces as necessary. Make sure the cooling shrouds are reinstalled. Figure 4-15. Cleanout Kit Installed on Blower Housing. 4.6 Section 5 Fuel System and Governor Section 5 Fuel System and Governor Description The Command horizontal twins use three different types of fuel systems; carbureted, electronic fuel injection (EFI), or gaseous. Gaseous fuel systems can be either liquefied petroleum gas (LPG or LP) or natural gas (NG). Some dual-fuel engines have a combination system, which allows the operator to select either gasoline or LP. This section covers the standard carbureted fuel systems. The gaseous systems are covered in subsection 5A and the EFI systems are covered in subsection 5B. The governor systems used are covered at the end of this section. WARNING: Explosive Fuel! Gasoline is extremely flammable and its vapors can explode if ignited. Store gasoline only in approved containers, in well ventilated, unoccupied buildings, away from sparks or flames. Do not fill the fuel tank while the engine is hot or running, since spilled fuel could ignite if it comes in contact with hot parts or sparks from ignition. Do not start the engine near spilled fuel. Never use gasoline as a cleaning agent. Fuel System Components The typical carbureted fuel system and related components include the following: · · · · · Fuel Tank Fuel Lines In-line Fuel Filter Fuel Pump Carburetor Fuel then enters the carburetor float bowl and is drawn into the carburetor body. There, the fuel is mixed with air. This fuel-air mixture is then burned in the engine combustion chamber. Fuel Recommendations General Recommendations Purchase gasoline in small quantities and store in clean, approved containers. A container with a capacity of 2 gallons or less with a pouring spout is recommended. Such a container is easier to handle and helps eliminate spillage during refueling. · Do not use gasoline left over from the previous season, to minimize gum deposits in your fuel system and to ensure easy starting. Do not add oil to the gasoline. Do not overfill the fuel tank. Leave room for the fuel to expand. 5 · · Fuel Type For best results, use only clean, fresh, unleaded gasoline with a pump sticker octane rating of 87 or higher. In countries using the Research fuel rating method, it should be 90 octane minimum. Unleaded gasoline is recommended as it leaves less combustion chamber deposits and reduces harmful exhaust emissions. Leaded gasoline is not recommended and must not be used on EFI engines, or on other models where exhaust emissions are regulated. Gasoline/Alcohol blends Gasohol (up to 10% ethyl alcohol, 90% unleaded gasoline by volume) is approved as a fuel for Kohler engines. Other gasoline/alcohol blends are not approved. Operation The fuel from the tank is moved through the in-line filter and fuel lines by the fuel pump. On engines not equipped with a fuel pump, the fuel tank outlet is located above the carburetor inlet allowing gravity to feed fuel to the carburetor. 5.1 Section 5 Fuel System and Governor Gasoline/Ether blends Methyl Tertiary Butyl Ether (MTBE) and unleaded gasoline blends (up to a maximum of 15% MTBE by volume) are approved as a fuel for Kohler engines. Other gasoline/ether blends are not approved. Fuel Filter Most engines are equipped with an in-line fuel filter. Periodically inspect the filter and replace with a genuine Kohler filter every 200 operating hours. Fuel Line In compliance with CARB Tier III Emission Regulations, carbureted engines with a "Family" identification number beginning with "6" or greater (See Figure 5-1), must use Low Permeation SAE 30 R7 rated fuel line; certified to meet CARB requirements. Standard fuel line may not be used. Order replacement hose by part number through a Kohler Engine Service Dealer. IMPORTANT ENGINE INFORMATION THIS ENGINE MEETS U.S. EPA AND CA 2005 AND LATER AND EC STAGE II (SN:4) EMISSION REGS FOR SI SMALL OFF­ROAD ENGINES FAMILY 6 KHXS.7252 PH TYPE APP DISPL. (CC) N11236 MODEL NO. SPEC. NO. SERIAL NO. BUILD DATE OEM PROD. NO. EMISSION COMPLIANCE PERIOD: EPA: CARB: CERTIFIED ON: REFER TO OWNER'S MANUAL FOR HP RATING, SAFETY, MAINTENANCE AND ADJUSTMENTS 1-800-544-2444 www.kohlerengines.com KOHLER CO. KOHLER, WISCONSIN USA Figure 5-1. "Family" Number Location. 5.2 Section 5 Fuel System and Governor Fuel System Tests When the engine starts hard, or turns over but will not start, it is possible that the problem is in the fuel system. To find out if the fuel system is causing the problem, perform the following tests. Troubleshooting ­ Fuel System Related Causes Test 1. Check the following: a. Make sure the fuel tank contains clean, fresh, proper fuel. b. Make sure the vent in fuel tank is open. c. Make sure the fuel valve is open. d. Make sure vacuum and fuel lines to fuel pump are secured and in good condition. 2. Check for fuel in the combustion chamber. a. Disconnect and ground spark plug leads. b. Close the choke on the carburetor. c. Crank the engine several times. d. Remove the spark plug and check for fuel at the tip. 3. Check for fuel flow from the tank to the fuel pump. a. Remove the fuel line from the inlet fitting of fuel pump. b. Hold the line below the bottom of the tank. Open the shut-off valve (if so equipped) and observe flow. 4. Check the operation of fuel pump. a. Remove the fuel line from the inlet fitting of carburetor. b. Crank the engine several times and observe flow. 2. If there is fuel at the tip of the spark plug, fuel is reaching the combustion chamber. If there is no fuel at the tip of the spark plug, check for fuel flow from the fuel tank (Test 3). Conclusion 5 3. If fuel does flow from the line, check for faulty fuel pump (Test 4). If fuel does not flow from the line, check the fuel tank vent, fuel pickup screen, in-line filter, shutoff valve, and fuel line. Correct any observed problem and reconnect the line. 4. If fuel does flow from the line, check for faulty carburetor. (Refer to the "Carburetor" portions of this section.) If fuel does not flow from the line, check for a clogged fuel line. If the fuel line is unobstructed, check for overfilled crankcase and/or oil in pulse line. If none of the checks reveal the cause of the problem, replace the pump. 5.3 Section 5 Fuel System and Governor Fuel Pump General These engines are equipped with either a pulse or mechanical fuel pump. See Figures 5-2 and 5-3. The pumping action is created by either the oscillation of positive and negative pressures within the crankcase through a hose, or by direct lever/pump actuation off rocker arm movement. The pumping action causes the diaphragm on the inside of the pump to pull fuel in on its downward stroke and to push it into the carburetor on its upward stroke. Internal check valves prevent fuel from going backward through the pump. Outlet Line (to Carburetor) Pulse Fuel Pump NOTE: On most models, the pulse line is connected to a fitting on the crankcase, while on early models, it is connected to the valve cover. 4. Install the new fuel pump using the hex flange screws. Torque the hex flange screws to 2.3 N·m (20 in. lb.). NOTE: Make sure the orientation of the new pump is consistent with the removed pump. Internal damage may occur if installed incorrectly. 5. Connect the pulse line to the pulse fitting. 6. Connect the fuel lines to the inlet and outlet fittings. Replacing the Mechanical Pump The mechanical pump is an integral part of the valve cover assembly and not serviced separately. See Figure 5-3. Inlet Line 1. Disconnect the fuel lines from the inlet and outlet fittings. 2. Follow the procedure for replacing the valve cover (Sections 9 and 11). 3. Reconnect the fuel lines to the inlet and outlet fittings. Outlet Line (to Carburetor) Pulse Line Figure 5-2. Pulse Style Fuel Pump. 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 18 in. from carburetor inlet. A 1.3 L/hr. (0.34 gal./hr.) fuel rate must be maintained at 5 Hz. Fuel Pump - Replacement Replacing the Pulse Fuel Pump Replacement pumps are available through your source of supply. To replace the pulse pump follow these steps: 1. Disconnect the fuel lines from the inlet and outlet fittings. 2. Remove the hex flange screws securing the fuel pump. 3. Remove the pulse line that connects the pump to the crankcase or valve cover. Figure 5-3. Mechanical Fuel Pump. Mechanical Fuel Pump Inlet Line 5.4 Section 5 Fuel System and Governor Carburetor General Engines in this series are equipped with Keihin fixed main jet carburetors. CH18-740 engines use a onebarrel carburetor. Most applications use a fuel shutoff solenoid installed in place of the fuel bowl retaining screw, and also contain an accelerator pump. All carburetors feature a self-relieving choke like or similar to the one shown in the exploded view on page 5.10. CH750 engines use a Keihin BK twobarrel carburetor on a matching intake manifold. This carburetor with related servicing and adjustments is covered beginning on page 5.11. WARNING: Explosive Fuel Gasoline is extremely flammable and its vapors can explode if ignited. Store gasoline only in approved containers, in well ventilated, unoccupied buildings, away from sparks or flames. Do not fill the fuel tank while the engine is hot or running, since spilled fuel could ignite if it comes in contact with hot parts or sparks from ignition. Do not start the engine near spilled fuel. Never use gasoline as a cleaning agent. Troubleshooting - Carburetor Related Causes Condition 1. Engine starts hard, runs roughly or stalls at idle speed. Possible Cause/Probable Remedy 1. Low idle fuel mixture (some models)/speed improperly adjusted. Adjust the low idle speed tab, then adjust the low idle fuel needle. 5 2. Engine runs rich (indicated by 2a. Clogged air cleaner. Clean or replace. black, sooty exhaust smoke, b. Choke partially closed during operation. Check the choke lever/ misfiring, loss of speed and power, linkage to ensure choke is operating properly. governor hunting, or excessive c. Low idle fuel mixture is improperly adjusted. Adjust low idle throttle opening). fuel needle (some models). d. Float level is set too high. Separate carburetor air horn from carburetor body, adjust float to specification. e. Dirt under the fuel inlet needle. Remove needle; clean needle and seat and blow with compressed air. f. Bowl vent or air bleeds plugged. Remove low idle fuel adjusting needle. Clean vent, ports, and air bleeds. Blow out all passages with compressed air. g. Leaky, cracked or damaged float. Submerge float to check for leaks. 3. Engine runs lean (indicated by 3a. Low idle fuel mixture is improperly adjusted. Adjust low idle misfiring, loss of speed and power, fuel needle (some models). governor hunting or excessive b. Float level is set too low. Separate carburetor air horn from throttle opening). carburetor body, adjust float specification. c. Idle holes plugged; dirt in fuel delivery channels. Remove low idle fuel adjusting needle. Clean main fuel jet and all passages; blow out with compressed air. 4. Fuel leaks from carburetor. 4a. b. c. d. Float level set too high. See Remedy 2d. Dirt under fuel inlet needle. See Remedy 2e. Bowl vents plugged. Blow out with compressed air. Carburetor bowl gasket leaks. Replace gasket. 5.5 Section 5 Fuel System and Governor Troubleshooting Checklist When the engine starts hard, runs roughly or stalls at low idle speed, check the following areas before adjusting or disassembling the carburetor. · Make sure the fuel tank is filled with clean, fresh gasoline. Make sure the fuel tank cap vent is not blocked and that it is operating properly. Make sure fuel is reaching the carburetor. This includes checking the fuel shut-off valve, fuel tank filter screen, in-line fuel filter, fuel lines and fuel pump for restrictions or faulty components as necessary. Make sure the air cleaner base and carburetor are securely fastened to the engine using gaskets in good condition. Make sure the air cleaner element (including precleaner if equipped) is clean and all air cleaner components are fastened securely. Make sure the ignition system, governor system, exhaust system, and throttle and choke controls are operating properly. Fuel Shut-off Solenoid When current is removed the pin extends blocking the main fuel jet and preventing fuel from entering the carburetor. One-Barrel Carburetor · · Two-Barrel Carburetor · · · Fuel Shut-off Solenoid Figure 5-4. Fuel Shut-off Solenoid. Below is a simple test, made with the engine off, that can determine if the solenoid is functioning properly: 1. Shut off fuel and remove the solenoid from the carburetor. When the solenoid is loosened and removed, gas will leak out of the carburetor. Have a container ready to catch the fuel. 2. Wipe the tip of the solenoid with a shop towel or blow it off with compressed air, to remove any remaining fuel. Take the 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 the power source is switched "off". Connect the positive power source lead to the red lead of the solenoid. Connect the negative power source lead to the solenoid bracket. 4. Turn the power source "on" and observe the pin in the center of the solenoid. The pin should retract with the power "on" and return to its original position with the power off. Test several times to verify operation. If the engine is hard-starting, runs roughly, or stalls at low idle speed, it may be necessary to adjust or service the carburetor. High Altitude Operation When operating the engine at altitudes of 1500 m (5000 ft.) and above, the fuel mixture tends to get overrich. This can cause conditions such as black, sooty exhaust smoke, misfiring, loss of speed and power, poor fuel economy, and poor or slow governor response. To compensate for the effects of high altitude, special high altitude jet kits are available. The kits include a new main jet, slow jet (where applicable), necessary gaskets and O-Rings. Refer to the parts manual for the correct kit number. Fuel Shut-off Solenoid Most carburetors are equipped with a fuel shut-off solenoid. The solenoid is attached in place of the fixed main jet screw on the flywheel side of the carburetor. See Figure 5-4. The solenoid has a spring-loaded pin that retracts when 12 volts is applied to the lead, allowing fuel flow through the main jet. 5.6 Section 5 Fuel System and Governor Carburetor Adjustments (CH18-740) General In compliance with government emission standards, the carburetor is calibrated to deliver the correct airto-fuel mixture to the engine under all operating conditions. The high-speed mixture is preset and cannot be adjusted. Pre-compliance carburetors contain a low idle fuel adjusting needle, on "certified" compliance carburetors, both the low and high speed mixture circuits are pre-established and cannot be adjusted. The low idle speed (RPM) is the only adjustment available. See Figures 5-5 and 5-6. Depending on model and application, engines may also be equipped with a "Governed Idle System." If equipped with a "Governed Idle System", refer to "Models with Governed Idle System" when performing any carburetor adjustment, as an additional step to the listed adjustment procedure(s) is required. Low Idle Speed Adjustment Low Idle Fuel Adjusting Needle NOTE: Carburetor adjustments should be made only after the engine has warmed up. Adjusting Low Idle Speed and Fuel (Some Models) To adjust the carburetor idle speed, see Figure 5-5 and follow these steps. 1. With the engine stopped, turn the low idle fuel adjusting needle in clockwise until it bottoms lightly. NOTE: The tip of the idle fuel adjusting needle is tapered to critical dimensions. Damage to the needle and the seat in the carburetor body will result if the needle is forced. 2. Now turn the adjusting needle out counterclockwise 1-1/2 turns. 3. Start the engine and run at half throttle for 5 to 10 minutes to warm up. The engine must be warm before making final settings. Check that the throttle and choke plates can fully open. NOTE: The carburetor has a self-relieving choke. Choke plate and shaft assembly is spring loaded. Check to make sure plate moves freely and is not binding and affecting idle fuel delivery. Main Jet Location 4. Place the throttle control into the "idle" or "slow" position. Turn the low idle speed adjusting screw in or out to obtain a low idle speed of 1200 RPM (± 75 RPM). Check the speed using a tachometer. NOTE: The actual low idle speed depends on the application. Refer to the equipment manufacturer's recommendations. The low idle speed for basic engines is 1200 RPM. To ensure best results when setting the low idle fuel needle, the low idle speed should be 1200 RPM (± 75 RPM). 5. Turn the low idle fuel adjusting needle in (slowly) until engine speed decreases and then back out approximately 3/4 turn to obtain the best low speed performance. Fuel Shut-Off Solenoid (Main Jet Location) Figure 5-6. "Certified" Compliance Carburetor. 6. Recheck the idle speed using a tachometer and readjust the speed as necessary. 5 Figure 5-5. Pre-Compliance Carburetor with Low Idle Adjustment. Low Idle Speed Adjustment 5.7 Section 5 Fuel System and Governor Models with Governed Idle System An optional governed idle control system is supplied on some engines. The purpose of this system is to maintain a desired idle speed regardless of ambient conditions (temperature, parasitic load, etc.) that may change. Engines with this feature contain a small secondary spring connected between the governor lever and the lower adjustment tab of the main bracket. See Figure 5-7. The system requires an additional procedure for setting the idle speed. If speed adjustments are required proceed as follows. 1. Make any necessary speed or control adjustments following the appropriate instructions covered in this section. 2. Move the throttle control to the idle position. Hold the governor lever away from the carburetor, or hold the throttle lever so it is tight against the idle speed adjusting screw, to negate the governor activation. See Figure 5-8. Check the speed with a tachometer and adjust it to 1500 RPM. 3. Release the governor lever and allow the engine to return to the governed idle speed. Check it with a tachometer against the equipment manufacturers recommended idle speed. Governed Idle Speed (RPM) is typically 300 RPM (approximate) higher than the low idle speed. If adjustment is necessary, bend the adjusting tab on the speed control assembly to set. See Figure 5-7. Figure 5-8. Holding Throttle Lever Against Idle Stop Screw (One-Barrel Carburetor). Hold Throttle Lever Against Screw Servicing Float It is not necessary to remove the carburetor from the engine to check and adjust the float. 1. Remove the air cleaner and breather hose. Refer to Section 9 ­ ``Disassembly". 2. Disconnect the fuel line from the carburetor. See Figure 5-9. 3. Clean dirt and debris from exterior of carburetor. 4. Remove the four screws holding the two carburetor halves together. Carefully lift the upper body off the carburetor body and disconnect choke linkage. Governed Idle Spring Tab Screws Fuel Line Figure 5-9. Carburetor Detail. Figure 5-7. Governed Idle Spring Location. 5. Hold the carburetor upper body so that the float assembly hangs vertically and rests lightly against the fuel inlet needle. The fuel inlet needle should be fully seated, but the needle tip should not be depressed. See Figure 5-10. 5.8 Section 5 Fuel System and Governor NOTE: The fuel inlet needle tip is spring loaded. Make sure the float assembly rests against the fuel inlet needle without depressing the tip. 6. The correct float height adjustment is 22 mm (0.86 in.), measured from the float bottom to the air horn casting. Adjust the float height by carefully bending the tab. NOTE: Be sure to measure from the casting surface, not the rubber gasket surface. 7. If proper float height adjustment cannot be achieved, check to see if the fuel inlet needle is dirty, obstructed or worn. Remove the brass screw and float assembly to remove the fuel inlet needle. Tab 2. Remove the four screws and carefully separate the air horn assembly from the carburetor body. 3. Loosen the screw securing the float assembly to the air horn and remove the float, float shaft and fuel inlet needle. 4. Remove the slow jet from the carburetor body. NOTE: The main jet is a fixed jet and can be removed if required. Fixed jets for high altitude are available. 5. Remove the black cap on the end of the choke shaft only if it is necessary to inspect and clean the shaft spring. 6. Remove the low idle speed adjusting screw and spring from the carburetor body. 7. In order to clean the ``off-idle'' vent ports and bowl vent thoroughly, use a good carburetor solvent (like GumoutTM). Blow clean compressed air through the idle adjusting needle hole. Be careful to use a suitable shop rag to prevent debris from hitting someone. 8. Remove the preformed rubber gasket only if it is to be replaced. If it is removed for any reason, replace it. 5 Float Figure 5-10. Carburetor Float Adjustment. 8. Once the proper float height is obtained, carefully lower the carburetor air horn assembly onto the carburetor body, connecting the choke linkage. Install the four screws. Torque the screws to 1.7 N·m (15 in. lb.). See Figure 5-9. 9. Connect the fuel line. 10. Install the breather hose and air cleaner assembly, following the steps in Section 11 ­ ``Reassembly". Inspection/Repair Carefully inspect all components and replace those that are worn or damaged. · Inspect the carburetor body for cracks, holes and other wear or damage. Inspect the float for cracks, holes, and missing or damaged float tabs. Check the float hinge and shaft for wear or damage. · · Inspect the fuel inlet needle and seat for wear or damage. · Inspect the tip of the low idle fuel adjusting needle for wear or grooves. · The choke plate is spring loaded. Check to make sure it moves freely on the shaft. Disassembly Disassemble the carburetor using the following steps. See Figure 5-11. 1. Remove the air cleaner, breather hose and carburetor. Refer to Section 9 ­ "Disassembly". 5.9 Section 5 Fuel System and Governor NOTE: The choke and throttle plate assemblies are staked and matched to the shafts at the factory. They are not serviceable items. Always use new gaskets when servicing or reinstalling carburetors. Repair kits are available which include new gaskets and other components. These kits are described on the next page. air horn. Tighten the screw. Check float height using the procedure found previously in the ``Adjustments'' subsection. 2. Install the slow jet with the stepped end toward the bottom of the carburetor. Make sure jet is fully seated. 3. Install the low idle adjusting needle and spring. 4. Assemble the upper body onto the lower carburetor body using the four screws. Torque the screws to 1.7 N·m (15 in. lb.). 5. Install the carburetor on the engine following the procedures in Section 11 ­ ``Reassembly.'' 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. Carburetor Upper Body (Choke) Self-relieving Choke Body Gasket (Formed Rubber) Slow Speed Jet Inlet Needle Valve Clip Float Pin Float Assembly (Kit) Carburetor Lower Body (Throttle) Main Jet Idle Fuel Adjusting Needle (some models) Solenoid Seat Fuel Shut-off Solenoid (Kit) Idle Speed Adjusting Screw Jet (Accelerator Pump Carburetor only) Accelerator Pump Cover Diaphragm Diaphragm Spring O-Ring Rubber Boot Bushing Return Spring 19 10 11 14 12 21 22 Accelerator Pump Version Only # Reassembly Reassemble the carburetor using the following steps. See Figure 5-11. 1. Assemble the fuel inlet needle to the float tab. Install the float, float shaft and inlet needle to the 2 1 3 4 5 6 15 8 7 9 17 See Note on Page 5.11 18 19 16 20 13 Figure 5-11. CH18-740 Carburetor ­ Exploded View. 5.10 Section 5 Fuel System and Governor Components such as the throttle and choke shaft assemblies, throttle plate, choke plate, low idle fuel needle, and others, are available separately. Always refer to the Parts Manual for the engine being serviced, to ensure the correct repair kits and replacement parts are ordered. Service/repair kits available for the carburetor and affiliated components are: Carburetor Repair Kit Float Kit High Altitude Kit (1525-3048 m/5,000-10,000 ft.) High Altitude Kit (over 3048 m/10,000 ft.) Solenoid Assembly Kit Accelerator Pump Seal and Bushing Kit Accelerator Pump Diaphragm Kit Choke Repair Kit # NOTE: If accelerator pump rod movement is restricted or corrosion exists in the pump rod housing hole; use a 0.153 in. (3.9 mm) or No. 23 drill and carefully clean (resize) the hole to restore proper operation. Blow out the hole with air and lightly lubricate with oil on reassembly. Slow & Mid-Range Circuit: At low speeds the engine operates only on the slow circuit. As a metered amount of air is drawn through the slow air bleed jets, fuel is drawn through the two main jets and further metered through the slow jets. Air and fuel are mixed in the body of the slow jet and exit to the transfer port. From the transfer port the air fuel mixture is delivered to the idle progression chamber. From the idle progression chamber the air fuel mixture is metered through the idle port passages. At low idle when the vacuum signal is weak, the air/fuel mixture is controlled by the setting of the idle fuel adjusting screws. This mixture is then mixed with the main body of air and delivered to the engine. As the throttle plate opening increases, greater amounts of air/fuel mixture are drawn in through the fixed and metered idle progression holes. As the throttle plate opens further the vacuum signal becomes great enough so the main circuit begins to work. Main (High-Speed) Circuit: At high speeds/loads the engine operates on the main circuit. As a metered amount of air is drawn through the four air jets, fuel is drawn through the main jets. The air and fuel are mixed in the main nozzles and then enter the main body of airflow, where further mixing of the fuel and air occurs. This mixture is then delivered to the combustion chamber. The carburetor has a fixed main circuit; no adjustment is possible. 5 Carburetor Keihin BK Two-Barrel Carburetor (CH750) The carburetor used on CH750 engines is a Keihin two-barrel side draft design with fixed main jets. See Figure 5-12. A self-relieving choke similar to that used on single venturi carburetors is also contained in the design. The circuits within the carburetor function as described following: Float Circuit: The fuel level in the bowl is maintained by the float and fuel inlet needle. The buoyant force of the float stops fuel flow when the engine is at rest. When fuel is being consumed, the float will drop and fuel pressure will push the inlet needle away from the seat, allowing more fuel to enter the bowl. When demand ceases, the buoyant force of the float will again overcome the fuel pressure, rising to the predetermined setting and stop the flow. Carburetor Adjustments Adjustment NOTE: Carburetor adjustments should be made only after the engine has warmed up. The carburetor is designed to deliver the correct fuelto-air mixture to the engine under all operating conditions. The main fuel jet is calibrated at the factory and is not adjustable*. The idle fuel adjusting needle is also set at the factory and normally does not need adjustment. Depending on model and application, engines may also be equipped with a "Governed Idle System." If equipped with a "Governed Idle System", refer to "Models with Governed Idle System" when performing any carburetor adjustment, as an additional step to the listed adjustment procedure(s) is required. 5.11 Section 5 Fuel System and Governor *NOTE: Engines operating at altitudes above approximately 1500 m (5000 ft.) may require a special ``high altitude'' main jet. Refer to ``High Altitude Operation.'' If, however, the engine is hard-starting or does not operate properly, it may be necessary to adjust or service the carburetor. Low Idle Fuel Adjustments (With Limiters) Low Idle Speed (RPM) Adjustment Screw 2. Place the throttle control into the "idle" or "slow" position. Adjust the low idle speed to 1200 RPM*. Follow the "Adjusting the Low Idle Speed (RPM)" procedure. 3. Low Idle Fuel Needle(s) Setting: Place the throttle into the "idle" or "slow" position. a. Turn one of the low idle fuel adjusting needles out (counterclockwise) from the preliminary setting until the engine speed decreases (rich). Note the position of the needle. Now turn the adjusting needle in (clockwise). The engine speed may increase, then it will decrease as the needle is turned in (lean). Note the position of the needle. Set the adjusting needle midway between the rich and lean settings. See Figure 5-13. b. Repeat the procedure on the other low idle adjustment needle. 4. Recheck/adjust the Low Idle Speed (RPM), to the specified setting. Lean Lean Fuel Solenoid Figure 5-12. Keihin Two-Barrel Carburetor. Carburetor Adjustment Low Idle Speed (RPM) Adjustment 1. Low Idle Speed (RPM) Setting: Place the throttle control into the "idle" or "slow" position. Set the low idle speed to 1200 RPM* (± 75 RPM) by turning the low idle speed adjusting screw in or out. Check the speed using a tachometer. *NOTE: The actual low idle speed depends on the application. Refer to the equipment manufacturer's recommendations. The low idle speed for basic engines is 1200 RPM. To ensure best results when setting the low idle fuel needle, the low idle speed should be 1200 RPM (± 75 RPM). Low Idle Fuel Adjustment NOTE: Engines will have fixed low idle or limiter caps on the two idle fuel adjusting needles. Step 3 can only be performed within the limits allowed by the cap. Do not attempt to remove the limiter caps. 1. Start the engine and run at half throttle for 5 to 10 minutes to warm up. The engine must be warm before doing steps 2, 3, and 4. Adjust to Midpoint Adjust to Midpoint Rich Rich Left Side Right Side Figure 5-13. Optimum Low Idle Fuel Settings. Models with Governed Idle System An optional governed idle control system is supplied on some engines. The purpose of this system is to maintain a desired idle speed regardless of ambient conditions (temperature, parasitic load, etc.) that may change. Engines with this feature contain a small secondary spring connected between the governor lever and the lower adjustment tab of the main bracket. See Figure 5-14. The system requires an additional procedure for setting the idle speed. If speed adjustments are required proceed as follows. 5.12 Section 5 Fuel System and Governor 1. Make any necessary speed or control adjustments following the appropriate instructions covered in this section. 2. Move the throttle control to the idle position. Hold the governor lever away from the carburetor, or hold the throttle lever so it is tight against the idle speed adjusting screw, to negate the governor activation. See Figure 5-15. Check the speed with a tachometer and adjust it to 1500 RPM. 3. Release the governor lever and allow the engine to return to the governed idle speed. Check it with a tachometer against the equipment manufacturers recommended idle speed. Governed Idle Speed (RPM) is typically 300 RPM (approximate) higher than the low idle speed. If adjustment is necessary, bend the adjusting tab on the speed control assembly to set. See Figure 5-14. Carburetor Servicing Float Replacement If symptoms described in the carburetor troubleshooting guide indicate float level problems, remove the carburetor from the engine to check and/ or replace the float. Use a float kit to replace the float, pin, float valve, clip and screw. 1. Perform the removal procedures for the Heavy Duty Air Cleaner and Carburetor outlined in Section 9 "Disassembly." 2. Clean the exterior surfaces of dirt or foreign material before disassembling the carburetor. Remove the four mounting screws and carefully separate the fuel bowl from the carburetor. Do not damage the inner or bowl O-Ring. Transfer any remaining fuel into an approved container. Save all parts. Fuel can also be drained prior to bowl removal by loosening/removal of the bowl drain screw. See Figure 5-16. 5 Governed Idle Spring Tab Fuel Bowl Figure 5-14. Governed Idle Spring Location. Bowl Drain Screw Figure 5-16. Fuel Bowl Removed From Carburetor. Hold Throttle Lever Against Screw Figure 5-15. Holding Throttle Lever Against Idle Stop Screw (Two-Barrel Carburetor). 5.13 Section 5 Fuel System and Governor 3. Remove the float pin screw and lift out the old float, pin and inlet needle. See Figure 5-17. Discard all of the parts. The seat for the inlet needle is not serviceable, and should not be removed. Figure 5-19. Installing Float Assembly. 7. Hold the carburetor body so the float assembly hangs vertically and rests lightly against the fuel inlet needle. The inlet needle should be fully seated but the center pin of the needle (on retainer clip end) should not be depressed. Check the float height adjustment. NOTE: The inlet needle center pin is spring loaded. Make sure the float rests against the fuel inlet needle without depressing the center pin. 8. The correct float height setting is 17 mm (0.669 in.) ± 1.5 mm (0.059 in.), measured from the float bottom to the body of the carburetor. See Figure 5-20. Replace the float if the height is different than the specified setting. DO NOT attempt to adjust by bending float tab. Figure 5-17. Removing Float and Inlet Needle. 4. Clean the carburetor bowl and inlet seat areas as required, before installing the new parts. 5. Attach the inlet needle to the plastic tang of the float with the wire clip. The formed 90° lip should point up, with the needle valve hanging down. See Figure 5-18. Figure 5-18. Float and Inlet Needle Details. 6. Install the float and inlet needle down into the seat and carburetor body. Install the new pivot pin through the float hinge and secure with the new retaining screw. See Figure 5-19. Figure 5-20. Checking Float Height. NOTE: Be sure to measure from the casting surface, not the rubber gasket, if still attached. 5.14 Section 5 Fuel System and Governor 9. When the proper float height is obtained, carefully reinstall the fuel bowl, using new O-Rings onto the carburetor. Secure with the four original screws. Torque the screws to 2.5 ± 0.3 N·m (23 ± 2.6 in. lb.). See Figure 5-21. NOTE: Further disassembly of the fuel bowl is not necessary unless the Fuel Solenoid Kit, or Fuel Bowl Kit (obtained separately), will also be installed. 2. Remove the float pin screw and lift out the old float, pin, and inlet needle. See Figure 5-23. Discard all the old parts. The seat for the inlet needle is not serviceable, and should not be removed. 5 Figure 5-21. Installing Fuel Bowl. 10. Install the carburetor and the heavy-duty air cleaner as outlined in Section 11 "Reassembly." Disassembly/Overhaul 1. Clean the exterior surfaces of dirt or foreign material before disassembling the carburetor. Remove the four mounting screws and separate the fuel bowl from the carburetor. Transfer any remaining fuel into an approved container. Remove and discard the old O-Rings. Fuel can also be drained prior to bowl removal by loosening/removal of the bowl drain screw. See Figure 5-22. Figure 5-23. Removing Float and Inlet Needle. 3. Use an appropriate size flat screwdriver, and carefully remove the two main jets from the carburetor. Note and mark the jets by location for proper reassembly. The main jets may be size/side specific. After the main jets are removed, the main nozzles can be removed out through the bottom of the main towers. Note the orientation/direction of the nozzles. The end with the two raised shoulders should be out/down adjacent to the main jets. Save the parts for cleaning and reuse. See Figure 5-24. Fuel Bowl Bowl Drain Screw Main Nozzles Figure 5-22. Fuel Bowl Removed From Carburetor. Main Jets Figure 5-24. Main Jets and Nozzles Removed. 5.15 Section 5 Fuel System and Governor 4. Remove the screw securing the flat washer and ground lead (if equipped), from the top of the carburetor; then carefully pull (lift) out the two slow jets. The slow jets may be sized/side specific, mark or tag for proper reassembly. Note the small O-Ring on the bottom of each jet. See Figures 5-25 and 5-26. Save parts for cleaning and reuse unless a Jet Kit is also being installed. Clean the slow jets using compressed air. Do not use wire or carburetor cleaner. 6. Clean the carburetor body, main jets, vent ports, seats, etc. using a good commercially available carburetor solvent. Keep away from plastic or rubber parts if non-compatible. Use clean, dry compressed air to blow out the internal channels and ports. Do not use metal tools or wire to clean orifices and jets. Inspect and thoroughly check the carburetor for cracks, wear, or damage. Inspect the fuel inlet seat for wear or damage. Check the spring loaded choke plate to make sure it moves freely on the shaft. 7. Clean the carburetor fuel bowl as required. 8. Install the two main nozzles into the towers of the carburetor body. The end of the main nozzles with the two raised shoulders should be out/ down (adjacent to the main jets). Make sure the nozzles are completely bottomed. Carefully install the main jets into the towers of the carburetor body on the appropriate side, as identified when removal was performed. See Figure 5-27. Figure 5-25. Removing Screw and Washer. Slow (Idle Fuel) Jets Nozzle End with Two Shoulders (Out/Down) O-Ring Figure 5-26. Slow Jets and O-Ring Detail. 5. Remove the idle speed (RPM) adjustment screw and spring from the carburetor. Discard the parts. NOTE: The carburetor is now disassembled for appropriate cleaning and installation of the parts in the overhaul kit. Further disassembly is not necessary. The throttle shaft assembly, fuel inlet seat, idle fuel adjustment screws with limiter, and carburetor body, are nonserviceable items and should not be removed. The choke shaft assembly is serviceable, however it should not be removed unless a Choke Repair Kit will be installed. 5.16 Main Jets Figure 5-27. Installing Main Nozzles and Main Jets. 9. Make sure the O-Ring near the bottom of each slow jet is new, or in good condition. Align and insert the two slow jets into the top of carburetor. See Figure 5-26. 10. Install the large flat retaining washer and secure with the mounting screw, attaching the ground lead if originally secured by the screw. 11. Install the new idle speed (RPM) adjustment screw and spring onto the carburetor. Thread in until 3 or 4 threads are exposed, as an initial adjustment. See Figure 5-28. Section 5 Fuel System and Governor Figure 5-28. Installing Idle Speed Adjusting Screw and Spring. 12. Attach the inlet needle to the plastic tang of the float with the wire clip. The formed 90° lip should point up, with the needle valve hanging down. See Figure 5-29. Figure 5-30. Installing Float Assembly. 14. Hold the carburetor body so the float assembly hangs vertically and rests lightly against the fuel inlet needle. The inlet needle should be fully seated but the center pin of the needle (on retainer clip end) should not be depressed. Check the float height adjustment. NOTE: The inlet needle center pin is spring loaded. Make sure the float rests against the fuel inlet needle without depressing the center pin. 15. The correct float height setting is 17 mm (0.669 in.) ± 1.5 mm (0.059 in.), measured from the float bottom to the body of the carburetor. See Figure 5-31. Replace the float if the height is different than the specified setting. Do not attempt to adjust by bending float tab. 5 Figure 5-29. Float and Inlet Needle Details. 13. Install the float and inlet needle down into the seat and carburetor body. Install the new pivot pin through the float hinge and secure with the new retaining screw. See Figure 5-30. Figure 5-31. Checking Float Height. NOTE: Be sure to measure from the casting surface, not the rubber gasket, if still attached. 5.17