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Home / Small Engines / Kohler Engines / Kohler CH20S

Kohler CH20S Specifications

Engine Model: Kohler Command CH20S

Engine Type: 4-cycle V-Twin cylinder gasoline engine

Total Displacement: 28 cu.in (624 cc)

Rated Engine Power: 20.5 Hp (15.3 kW) at 3600 rpm

Carburetor Type: One-barrel, fixed main jet

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General Technical Data

Engine Model .............. Kohler Command CH20S
Engine Type .............. 4-cycle V-Twin cylinder horizontal shaft air-cooled gasoline engine
Number of Cylinders .............. 2
Displacement, cc (cu.in) .............. 624 (38.0)
Piston Bore, mm (in) .............. 77.0 (3.03)
Engine Stroke, mm (in) .............. 67.0 (2.64)
Maximum Engine Power, hp (kW) .............. 20.5 (15.3)
Maximum Engine Speed, rpm .............. 3600
Peak Torque, Nm (ft-lb) .............. 44.3 (32.7)
Torque Speed, rpm .............. 2200
Compression Ratio .............. 8.5:1
Compression Ratio .............. 8.5:1
Lubrication System .............. Full pressure
Oil Filter Type .............. Full-flow
Air Cleaner Type .............. Replaceable, paper element
Ignition System .............. Electronic magneto
Starting System .............. Electric starter
Electrical System Rating, Volts .............. 12

Fuel System

Fuel System Type .............. Carburetor
Carburetor Model .............. Keihin
Carburetor Type .............. One-barrel, fixed main jet
Fuel Pump Type .............. Pulse, mechanical
Fuel Filter Type .............. In-line
Governor Type .............. Mechanical

Dimensions and Weight

Overall Length, mm (in) .............. 349 (13.8)
Overall Width, mm (in) .............. 448 (17.7)
Overall Height, mm (in) .............. 481 (19.0)
Dry weight, kg (lbs) .............. 41.0 (90)

Cylinder Block

Cylinder Bore Inside Diameter (Std), mm (in) .............. 77.000-77.025 (3.0315-3.0325)
Cylinder Bore Inside Diameter (Max), mm (in) .............. 77.063 (3.0340)
Cylinder Bore (Max Out of Round), mm (in) .............. 0.12 (0.0047)
Crankshaft End Play (Free), mm (in) .............. 0.070-0.590 (0.0028-0.0230)
Crankshaft Bore (Crankcase), mm (in) .............. 40.965-41.003 (1.6128-1.6143)
Crankshaft Bore (Closure Plate), mm (in) .............. 40.987-40.974 (1.6136-1.6131)
Crankshaft Bore to Crankshaft Clearance, mm (in) .............. 0.039-0.074 (0.0015-0.0029)
Connecting Rod Journal Outside Diameter, mm (in) .............. 35.955-35.973 (1.4156-1.4163)
Connecting Rod to Crankpin Clearance, mm (in) .............. 0.030-0.055 (0.0012-0.0022)
Connecting Rod to Crankpin Side Clearance, mm (in) .............. 0.26-0.63 (0.0102-0.0248)
Connecting Rod to Piston Pin Clearance, mm (in) .............. 0.015-0.028 (0.0006-0.0011)
Camshaft End Play, mm (in) .............. 0.076-0.127 (0.0030-0.0050)
Camshaft Clearance, mm (in) .............. 0.025-0.063 (0.0010-0.0025)
Camshaft Bore Inside Diameter, mm (in) .............. 20.000-20.025 (0.7874-0.7884)
Camshaft Bearing Outside Diameter, mm (in) .............. 19.962-19.975 (0.7859-0.7864)

Cylinder Head and Valves

Cylinder Head (Max Out of Flatness), mm (in) .............. 0.076 (0.003)
Hydraulic Valve Lifter to Crankcase Clearance, mm (in) .............. 0.0241-0.0501 (0.0009-0.0020)
Valve Stem to Valve Guide Clearance (Intake), mm (in) .............. 0.038-0.076 (0.0015-0.0030)
Valve Stem to Valve Guide Clearance (Exhaust), mm (in) .............. 0.050-0.088 (0.0020-0.0035)
Valve Guide Inside Diameter, mm (in) .............. 7.038-7.058 (0.2771-0.2779)
Valve Minimum Lift (Intake), mm (in) .............. 8.07 (0.3177)
Valve Minimum Lift (Exhaust), mm (in) .............. 8.07 (0.3177)
Valve Face Angle, degrees .............. 45
Valve Seat Angle, degrees .............. 89
Valve Insert Outside Diameter (Intake), mm (in) .............. 36.987-37.013 (1.4562-1.4572)
Valve Insert Outside Diameter (Exhaust), mm (in) .............. 32.987-33.013 (1.2987-1.2997)
Valve Guide Depth, mm (in) .............. 6.50 (0.2559)
Valve Head Diameter (Intake), mm (in) .............. 33.37-33.63 (1.3138-1.3240)
Valve Head Diameter (Exhaust), mm (in) .............. 29.37-29.63 (1.1563-1.1665)
Valve Stem Diameter (Intake), mm (in) .............. 6.982-7.000 (0.2749-0.2756)
Valve Stem Diameter (Exhaust), mm (in) .............. 6.970-6.988 (0.2744-0.2751)

Piston and Piston Rings

Piston Outside Diameter (Std), mm (in) .............. 76.967-76.985 (3.0302-3.0309)
Piston Outside Diameter (Wear Limit), mm (in) .............. 76.840 (3.0252)
Piston to Cylinder Bore Clearance, mm (in) .............. 0.014-0.057 (0.0005-0.0022)
Piston to Piston Pin Clearance, mm (in) .............. 0.006-0.017 (0.0002-0.0007)
Piston Pin Bore Inside Diameter, mm (in) .............. 17.006-17.012 (0.6695-0.6698)
Piston Pin Outside Diameter, mm (in) .............. 16.995-17.000 (0.6691-0.6693)
Top Ring Groove Clearance, mm (in) .............. 0.040-0.080 (0.0016-0.0031)
Second Ring Groove Clearance, mm (in) .............. 0.040-0.080 (0.0016-0.0031)
Oil Ring Groove Clearance, mm (in) .............. 0.060-0.202 (0.0024-0.0080)
Top Ring End Gap, mm (in) .............. 0.25-0.45 (0.0100-0.0177)
Second Ring End Gap, mm (in) .............. 0.25-0.45 (0.0100-0.0177)

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