Kohler CH20

Kohler CH20The Kohler CH20/CH20S is a 624 cc, (38.0 cu·in) V-twin air-cooled four-stroke internal combustion gasoline engine from the Command PRO series, manufactured by Kohler Co.

The Kohler CH20 engine has an OHV (overhead valve) design, an aluminum block with cast iron cylinder liners, a horizontal PTO-shaft, pressurized lubrication system. This engine is equipped with a carburetor (Nikki or Keihin) with a fixed main jet and electronic ignition system.

The cylinder bore and the piston stroke are 77.0 mm (3.03 in) and 67.0 mm (2.64 in), respectively. Compression ratio rating is 8.5:1.

The Kohler CH20 engine produced 20.8 PS (15.3 KW; 20.5 HP) at 3,600 rpm of horsepower and 44.3 Nm (4.5 kg·m; 32.7 ft·lb) at 2,400 rpm.

The breakdown of the engine code is as follows:

  • C – Command series
  • H – Horizontal PTO shaft
  • 20 – Numerical designation
  • S – Electric start

General information

Engine Specifications
ModelCommand PRO CH20
Type4-stroke, OHV, V-twin
Displacement624 cm 3 (38.0 cu-in)
Max. horsepower 20.3 PS (14.9 KW; 20.0 HP) at 3,600 rpm
20.8 PS (15.3 KW; 20.5 HP) at 3,600 rpm
Max. torque44.3 Nm (4.5 kg·m; 32.7 ft·lb) at 2,400 rpm
Fuel systemCarburetor with a fixed main jet (Nikki or Keihin)
Cooling systemForced-air
Ignition systemElectronic ignition system
Lubricating systemPressurized lubrication
Starting systemElectric starter
Fuel usedUnleaded gasoline (octane number 86 or higher)
Dimensions (L x W X H)355 x 451 x 483 mm (14.0 x 17.7 x 19.0 in)
Dry weight41.0 kg (90.0 lbs)

Cylinder Block and Head

Cylinder block
Compression ratio:8.5:1
Bore x Stroke77.0 mm X 67.0 mm (3.03 x 2.64 in)
Sleeve internal diameter77.000-77.025 mm (3.0315-3.0325 in)
Number of piston rings (compression / oil):2 / 1
Thrust face outer diameter76.943-76.961 mm (3.0292-3.0299 in)
Piston pin outer diameter16.995-17.000 mm (0.6691-0.6693 in)
Ring-to-groove side clearance:Top0.040-0.080 mm (0.0016-0.0031 in)
Second0.040-0.080 mm (0.0016-0.0031 in)
Oil0.060-0.202 mm (0.0024-0.0080 in)
Ring end gap:Top0.250-0.450 mm (0.0098-0.0177 in)
Second0.250-0.450 mm (0.0098-0.0177 in)
Crankshaft main journal diameter:40.913-40.935 mm (1.6107-1.6116 in)
Crankpin journal diameter:35.955-35.973 mm (1.4155-1.4163 in)
Cylinder Head
Valve Arrangement:OHV, gear drive
Valves:4 (2 per cylinder)
Valve head diameter:INTAKE33.370-33.630 mm (1.3138-1.324 in)
EXHAUST29.370-29.630 mm (1.1563-1.1665 in)
Stem outer diameter:INTAKE6.982-7.000 mm (0.2749-0.2756 in)
EXHAUST6.970-6.988 mm (0.2744-0.2751 in)

Tightening torque specs

Tightening torque specs
Cylinder head Nut (torque in 2 increments):
Step 1: 16.9 Nm (1.72 kg·m; 12.5 ft·lb)
Step 2: 35.5 Nm (3.62 kg·m; 26.2 ft·lb)
Bolt (torque in 2 increments)
Step 1: 22.6 Nm (2.31 kg·m; 16.7 ft·lb)
Step 2: 41.8 Nm (4.26 kg·m; 30.8 ft·lb)
Flywheel66.4 Nm (6.77 kg·m; 49 ft·lb)
Spark plug27 Nm (2.75 kg·m; 20.0 ft·lb)

Service Information

Oil system
Oil typeAPI SG, SH, SJ, or higher
Recommended oilSAE 10W-30
Oil capacity W/o oil filter: 1.7 L (1.8 US. qt, 1.5 Imp. qt.)
With oil filter: 1.9 L (2.0 US.qts, 1.7 Imp. qts)
Ignition system
Spark plugChampion RC12YC
Spark plug gap0.76 mm (0.030 in)
Ignition module air gap0.280-0.330 mm (0.011-0.013 in)
Author: Sergei Wers
About: Co-founder and CEO of a multi-brand auto repair shop (engine repair, chassis repair, body repair and painting) for over 15 years. I have been developing internet sites with technical specifications for more than seven years.

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