Kohler Command Ch18 Ch20 Ch22 Ch23 Ch25 Ch26 Ch730 Ch740 Ch745 Ch750 HORIZONTAL CRANKSHAFT Engine* Factory Service / Repair/ Wor

CH18-CH25, CH620-CH730, CH740, CH750 Service Manual 2 Safety 3 Maintenance 5 Speciﬁcations 15 Tools and Aids 18 Troubleshooting 22 Air Cleaner/Intake 23 Fuel System 29 Governor System 31 Lubrication System 33 Electrical System 49 Starter System 58 Clutch 60 Disassembly/Inspection and Service 75 Reassembly IMPORTANT: Read all safety precautions and instructions carefully before operating equipment. Refer to operating instruction of equipment that this engine powers. Ensure engine is stopped and level before performing any maintenance or service. 1 24 690 06 Rev. J KohlerEngines.com

Safety 2 24 690 06 Rev. J KohlerEngines.com SAFETY PRECAUTIONS WARNING: A hazard that could result in death, serious injury, or substantial property damage. CAUTION: A hazard that could result in minor personal injury or property damage. NOTE: is used to notify people of important installation, operation, or maintenance information. WARNING Explosive Fuel can cause fires and severe burns. Do not fill fuel tank while engine is hot or running. 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. Spilled fuel could ignite if it comes in contact with hot parts or sparks from ignition. Never use gasoline as a cleaning agent. WARNING Rotating Parts can cause severe injury. Stay away while engine is in operation. Keep hands, feet, hair, and clothing away from all moving parts to prevent injury. Never operate engine with covers, shrouds, or guards removed. WARNING Carbon Monoxide can cause severe nausea, fainting or death. Avoid inhaling exhaust fumes. Engine exhaust gases contain poisonous carbon monoxide. Carbon monoxide is odorless, colorless, and can cause death if inhaled. WARNING Accidental Starts can cause severe injury or death. Disconnect and ground spark plug lead(s) before servicing. Before working on engine or equipment, disable engine as follows: 1) Disconnect spark plug lead(s). 2) Disconnect negative (–) battery cable from battery. WARNING Hot Parts can cause severe burns. Do not touch engine while operating or just after stopping. Never operate engine with heat shields or guards removed. WARNING Cleaning Solvents can cause severe injury or death. Use only in well ventilated areas away from ignition sources. Carburetor cleaners and solvents are extremely flammable. Follow cleaner manufacturer’s warnings and instructions on its proper and safe use. Never use gasoline as a cleaning agent. CAUTION Electrical Shock can cause injury. Do not touch wires while engine is running. CAUTION Damaging Crankshaft and Flywheel can cause personal injury. Using improper procedures can lead to broken fragments. Broken fragments could be thrown from engine. Always observe and use precautions and procedures when installing flywheel. CAUTION Failure to utilize or reassemble debris screen as designed could result in debris screen failure and serious personal injury. WARNING Uncoiling Spring can cause severe injury. Wear safety goggles or face protection when servicing retractable starter. Retractable starters contain a powerful, recoil spring that is under tension. Always wear safety goggles when servicing retractable starters and carefully follow instructions in Retractable Starter for relieving spring tension.

Maintenance 3 24 690 06 Rev. J KohlerEngines.com MAINTENANCE INSTRUCTIONS WARNING Before working on engine or equipment, disable engine as follows: 1) Disconnect spark plug lead(s). 2) Disconnect negative (–) battery cable from battery. Accidental Starts can cause severe injury or death. Disconnect and ground spark plug lead(s) before servicing. Normal maintenance, replacement or repair of emission control devices and systems may be performed by any repair establishment or individual; however, warranty repairs must be performed by a Kohler authorized dealer. MAINTENANCE SCHEDULE Weekly ● Check heavy-duty air cleaner element. Air Cleaner/Intake Every 25 Hours or Annually¹ ● Service/replace low-profile precleaner. Air Cleaner/Intake Every 100 Hours or Annually¹ ● Replace low-profile air cleaner element. Air Cleaner/Intake ● Change oil. Lubrication System/Clutch ● Remove cooling shrouds and clean cooling areas. Air Cleaner/Intake ● Check oil cooler fins, clean as necessary (if equipped). Lubrication System Every 200 Hours ● Change oil filter. Lubrication System ● Replace fuel filter. Every 250 Hours¹ ● Replace heavy-duty air cleaner element and check inner element. Air Cleaner/Intake Every 500 Hours¹ ● Replace heavy-duty inner air cleaner element. Air Cleaner/Intake ● Replace spark plugs and set gap. Electrical System Every 500 Hours 2 ● Have crankshaft spline lubricated. 1 Perform these procedures more frequently under severe, dusty, dirty conditions. 2 Have a Kohler authorized dealer perform this service. REPAIRS/SERVICE PARTS Kohler genuine service parts can be purchased from Kohler authorized dealers. To find a local Kohler authorized dealer visit KohlerEngines.com or call 1-800-544-2444 (U.S. and Canada).

Maintenance 4 24 690 06 Rev. J KohlerEngines.com OIL RECOMMENDATIONS We recommend use of Kohler oils for best performance. Other high-quality detergent oils (including synthetic) of API (American Petroleum Institute) service class SJ or higher are acceptable. Select viscosity based on air temperature at time of operation as shown in table below. FUEL RECOMMENDATIONS WARNING Explosive Fuel can cause fires and severe burns. Do not fill fuel tank while engine is hot or running. 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. Spilled fuel could ignite if it comes in contact with hot parts or sparks from ignition. Never use gasoline as a cleaning agent. NOTE: E15, E20 and E85 are NOT approved and should NOT be used; effects of old, stale or contaminated fuel are not warrantable. Fuel must meet these requirements: ● Clean, fresh, unleaded gasoline. ● Octane rating of 87 (R+M)/2 or higher. ● Research Octane Number (RON) 90 octane minimum. ● Gasoline up to 10% ethyl alcohol, 90% unleaded is acceptable. ● Methyl Tertiary Butyl Ether (MTBE) and unleaded gasoline blend (max 15% MTBE by volume) are approved. ● Do not add oil to gasoline. ● Do not overfill fuel tank. ● Do not use gasoline older than 30 days. STORAGE If engine will be out of service for 2 months or more follow procedure below. 1. Add Kohler PRO Series fuel treatment or equivalent to fuel tank. Run engine 2-3 minutes to get stabilized fuel into fuel system (failures due to untreated fuel are not warrantable). 2. Change oil while engine is still warm from operation. Remove spark plug(s) and pour about 1 oz. of engine oil into cylinder(s). Replace spark plug(s) and crank engine slowly to distribute oil. 3. Disconnect negative (-) battery cable. 4. Store engine in a clean, dry place.

Speciﬁcations 5 24 690 06 Rev. J KohlerEngines.com Engine Dimensions with Low-Proﬁle Air Cleaner Dimensions in millimeters. Inch equivalents shown in [ ].

Speciﬁcations 6 24 690 06 Rev. J KohlerEngines.com SOLENOID SHIFT STARTER 15.58 [.613] SPARK PLUG 526.49 [20.728] PRIMARY AIR FILTER ELEMENT REMOVAL 414.17 [16.306] SAFETY AIR FILTER ELEMENT REMOVAL 130.00 [5.118] AIR FILTER COVER ASSEMBLY REMOVAL 272.17 [10.715] 304.48 [11.987] 424.61 [16.717] 135.00 [5.315] AIR FILTER RAIN CAP REMOVAL 93.33 [3.674] OIL FILL LOCATION PULSE FUEL PUMP CRANKSHAFT 15.70 [.618] OIL FILTER REMOVAL 124.34 [4.895] 184.20 [7.252] 92.10 [3.626] CRANKSHAFT MOUNTING HOLE “A” ENGINE 3/8-16 UNC 2B 19.05 [.750] 1/4 IN. SQ KEYWAY 54.00 [2.126] 115.74 [4.557] 42.26 [1.664] OIL DIPSTICK 626.92 [24.682] 1/4 IN. SQ KEYWAY Ø 25.56 [1.125] 7/16-20 UNF 2B (INCH) 38.10 (1.500) 70.52 [2.776] 155.58 [6.125] 100.00 [3.937] 89.00 [3.504] ENGINE MOUNTING SURFACE 514.05 [20.238] ENGINE MOUNTING SURFACE 7/16-14 UNC 2B (INCH) 21.0 [.827] Ø 196.85 [7.75]B.C. 3/8-16 UNC 2B (INCH) 17.0 [.669] Ø 165.1 [6.50]B.C. LIFT STRAP 285.90 [11.256] 50.85 [2.002] 30˚ 30˚ 301.36 [11.864] 2X OIL DRAIN PLUG 3/8 NPT (INCH) MOUNTING HOLE “A” 440.88 [17.357] LIFT STRAP 89.00 [3.504] Engine Dimensions with Heavy-Duty Air Cleaner Dimensions in millimeters. Inch equivalents shown in [ ].

Specifications 7 24 690 06 Rev. J KohlerEngines.com ENGINE IDENTIFICATION NUMBERS Kohler engine identification numbers (model, specification and serial) should be referenced for efficient repair, ordering correct parts, and engine replacement. Model ..................... CH620 Command Engine Horizontal Shaft Numerical Designation Specification ............... CH620-0001 Serial ..................... 4323500328 Year Manufactured Code Factory Code Code Year 43 2013 44 2014 45 2015 GENERAL SPECIFICATIONS 3,6 CH18/CH20/ CH22/ CH620/CH621/ CH640/CH641 CH22/CH23/ CH620 7 / CH640 7 / CH670/CH680 CH25/ CH730/ CH740 CH750 Bore 77 mm (3.03 in.) 80 mm (3.15 in.) 83 mm (3.27 in.) Stroke 67 mm (2.64 in.) 69 mm (2.7 in.) Displacement 624 cc (38 cu. in.) 674 cc (41 cu. in.) 725 cc (44 cu. in.) 747 cc (46 cu. in.) Oil Capacity (refill) 1.6-1.8 L (1.7-1.9 U.S. qt.) Maximum Angle of Operation (@ full oil level) 4 25° TORQUE SPECIFICATIONS 3,5 CH18/CH20/ CH22/ CH620/CH621/ CH640/CH641 CH22/CH23/ CH620/ CH640/ CH670/CH680 CH25/ CH730/ CH740 CH750 Blower Housing and Sheet Metal M5 Fasteners 6.2 N·m (55 in. lb.) into new holes 4.0 N·m (35 in. lb.) into used holes M6 Fasteners 10.7 N·m (95 in. lb.) into new holes 7.3 N·m (65 in. lb.) into used holes Carburetor and Intake Manifold Intake Manifold Mounting Fastener (torque in 2 increments) first to 7.4 N·m (66 in. lb.) finally to 9.9 N·m (88 in. lb.) M6 Mounting Screw 6.2-7.3 N·m (55-65 in. lb.) Adapter (for Heavy-Duty Air Cleaner) Mounting Fastener 7.3 N·m (65 in. lb.) Closure Plate Fastener 24.4 N·m (216 in. lb.) 3 Values are in Metric units. Values in parentheses are English equivalents. 4 Exceeding maximum angle of operation may cause engine damage from insufficient lubrication. 5 Lubricate threads with engine oil prior to assembly. 6 Any and all horsepower (hp) references by Kohler are Certified Power Ratings and per SAE J1940 & J1995 hp standards. Details on Certified Power Ratings can be found at KohlerEngines.com. 7 CH620/CH640 engines changed from 624cc to 674cc; displacement can be confirmed on engine nameplate.

Specifications 8 24 690 06 Rev. J KohlerEngines.com TORQUE SPECIFICATIONS 3,5 CH18/CH20/ CH22/ CH620/CH621/ CH640/CH641 CH22/CH23/ CH620/ CH640/ CH670/CH680 CH25/ CH730/ CH740 CH750 Connecting Rod Cap Fastener (torque in increments) 8 mm straight shank 8 mm step-down 6 mm straight shank 22.7 N·m (200 in. lb.) 14.7 N·m (130 in. lb.) 11.3 N·m (100 in. lb.) Crankcase Breather Cover Fastener 7.3 N·m (65 in. lb.) Oil Drain Plug 13.6 N·m (10 ft. lb.) Cylinder Head Fastener (torque in 2 increments) Nut first to 16.9 N·m (150 in. lb.) finally to 35.5 N·m (315 in. lb.) Bolt (torque in 2 increments) first to 22.6 N·m (200 in. lb.) finally to 41.8 N·m (370 in. lb.) Rocker Arm Screw 18.1 N·m (160 in. lb.) Flywheel Fan Fastener 9.9 N·m (88 in. lb.) Flywheel Retaining Screw 66.4 N·m (49 ft. lb.) Fuel Pump-Pulse Fastener 2.3 N·m (20 in. lb.) Governor Lever Nut 6.8 N·m (60 in. lb.) Ignition Spark Plug 27 N·m (20 ft. lb.) Module Fastener 4.0-6.2 N·m (35-55 in. lb.) Rectifier-Regulator Fastener 1.4 N·m (12.6 in. lb.) Muffler Retaining Nut 24.4 N·m (216 in. lb.) Oil Cooler Adapter Nipple 27 N·m (20 ft. lb.) Oil Sentry ™ Pressure Switch 4.5 N·m (40 in. lb.) Solenoid (Starter) Mounting Hardware Nippondenso Starter Delco-Remy Starter 6.0-9.0 N·m (53-79 in. lb.) 4.0-6.0 N·m (35-53 in. lb.) Nut, Positive (+) Brush Lead Nippondenso Starter Delco-Remy Starter 8.0-12.0 N·m (71-106 in. lb.) 8.0-11.0 N·m (71-97 in. lb.) 3 Values are in Metric units. Values in parentheses are English equivalents. 5 Lubricate threads with engine oil prior to assembly.

Speciﬁcations 9 24 690 06 Rev. J KohlerEngines.com TORQUE SPECIFICATIONS 3,5 CH18/CH20/ CH22/ CH620/CH621/ CH640/CH641 CH22/CH23/ CH620/ CH640/ CH670/CH680 CH25/ CH730/ CH740 CH750 Speed Control Bracket Fastener 10.7 N·m (95 in. lb.) into new holes 7.3 N·m (65 in. lb.) into used holes Starter Assembly Thru Bolt Inertia Drive Nippondenso Solenoid Shift Delco-Remy Solenoid Shift 4.5-5.7 N·m (40-50 in. lb.) 4.5-7.5 N·m (40-84 in. lb.) 5.6-9.0 N·m (49-79 in. lb.) Mounting Screw 15.3 N·m (135 in. lb.) Brush Holder Mounting Screw 2.5-3.3 N·m (22-29 in. lb.) Stator Mounting Screw 6.2 N·m (55 in. lb.) Valve Cover Gasket Style Cover Fastener 3.4 N·m (30 in. lb.) Black O-Ring Style Cover Fastener w/Shoulder Screws w/Flange Screws and Spacers 5.6 N·m (50 in. lb.) 9.9 N·m (88 in. lb.) Yellow or Brown O-Ring Style Cover Fastener w/Integral Metal Spacers 6.2 N·m (55 in. lb.) CLEARANCE SPECIFICATIONS 3 CH18/CH20/ CH22/ CH620/CH621/ CH640/CH641 CH22/CH23/ CH620/ CH640/ CH670/CH680 CH25/ CH730/ CH740 CH750 Camshaft End Play (w/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 Max. Wear Limit 20.000/20.025 mm (0.7874/0.7884 in.) 20.038 mm (0.7889 in.) Bearing Surface O.D. New Max. Wear Limit 19.962/19.975 mm (0.7859/0.7864 in.) 19.959 mm (0.7858 in.) Connecting Rod Connecting Rod-to-Crankpin Running Clearance New Max. Wear Limit 0.030/0.055 mm (0.0012/0.0022 in.) 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 Max. Wear Limit 17.015/17.023 mm (0.6699/0.6702 in.) 17.036 mm (0.6707 in.) 3 Values are in Metric units. Values in parentheses are English equivalents. 5 Lubricate threads with engine oil prior to assembly.

Speciﬁcations 10 24 690 06 Rev. J KohlerEngines.com CLEARANCE SPECIFICATIONS 3 CH18/CH20/ CH22/ CH620/CH621/ CH640/CH641 CH22/CH23/ CH620/ CH640/ CH670/CH680 CH25/ CH730/ CH740 CH750 Crankcase Governor Cross Shaft Bore I.D. 6 mm Shaft New Max. Wear Limit 8 mm Shaft New Max. Wear Limit 6.025/6.050 mm (0.2372/0.2382 in.) 6.063 mm (0.2387 in.) 8.025/8.075 mm (0.3159/0.3179 in.) 8.088 mm (0.3184 in.) Crankshaft End Play (free) 0.070/0.590 mm (0.0028/0.0230 in.) End Play (w/thrust bearing components) 0.070/1.190 mm (0.0028/0.0468 in.) Except CH25 Engines Below Serial No. 2403500008 0.050/0.750 mm (0.0020/0.0295 in.) Bore (in crankcase) New Max. Wear Limit 40.965/41.003 mm (1.6128/1.6143 in.) 41.016 mm (1.6148 in.) Crankshaft to Sleeve Bearing (crankcase) Running Clearance-New 0.03/0.09 mm (0.0012/0.0035 in.) 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 O.D. - Max. Wear Limit Max. Taper Max. Out-of-Round 40.913/40.935 mm (1.6107/1.6116 in.) 40.84 mm (1.608 in.) 0.022 mm (0.0009 in.) 0.025 mm (0.0010 in.) Closure Plate End Main Bearing Journal O.D. - New O.D. - Max. Wear Limit Max. Taper Max. Out-of-Round 40.913/40.935 mm (1.6107/1.6116 in.) 40.84 mm (1.608 in.) 0.022 mm (0.0009 in.) 0.025 mm (0.0010 in.) Connecting Rod Journal O.D. - New O.D. - Max. Wear Limit Max. Taper Max. Out-of-Round 35.955/35.973 mm (1.4156/1.4163 in.) 35.94 mm (1.415 in.) 0.018 mm (0.0007 in.) 0.025 mm (0.0010 in.) T.I.R. PTO End, Crank in Engine Entire Crank, in V-Blocks 0.279 mm (0.0110 in.) 0.10 mm (0.0039 in.) Cylinder Bore Bore I.D. New 77.000/ 77.025 mm (3.0315/ 3.0325 in.) 80.000/ 80.025 mm (3.1496/ 3.1506 in.) 82.988/83.013 mm (3.2672/3.2682 in.) Max. Wear Limit 77.063 mm (3.0340 in.) 80.065 mm (3.1522 in.) 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 Max. Out-of-Flatness 0.076 mm (0.003 in.) 0.1 mm (0.004 in.) 3 Values are in Metric units. Values in parentheses are English equivalents.

Kohler Command Ch18 Ch20 Ch22 Ch23 Ch25 Ch26 Ch730 Ch740 Ch745 Ch750 HORIZONTAL CRANKSHAFT Engine* Factory Service / Repair/ Wor

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