Kohler CH740

The Kohler CH740 is a 725 cc, (44.2 cu·in) V-twin air-cooled four-stroke internal combustion gasoline engine from the Command PRO series, manufactured by Kohler Co.

The Kohler CH740 engine has an OHV (overhead valve) design, an aluminum block with cast iron cylinder liners, horizontal PTO-shaft, pressurized lubrication system. This engine is equipped with a carburetor (Nikki or Keihin) with a fixed main jet and one of these ignition systems: CDI/MDI, ASAM/DSAM, DSAI (Digital Spark Advance Ignition).

The cylinder bore and the piston stroke are 83.0 mm (3.27 in) and 67.0 mm (2.64 in), respectively. Compression ratio rating is 9.0:1. The CH740 engine produces 25.3 PS (18.6 kW; 25.0 HP) at 3,600 rpm of horsepower and 53.1 N·m (5.4 kg·m, 39.1 ft·lb) at 3,000 rpm of torque, or 27.3 PS (20.1 kW; 27.0 HP) at 3,600 rpm of horsepower and 57.3 Nm (5.84 kg·m; 42.29 ft·lb) at 3,000 rpm of peak torque, depending on the engine version.

The breakdown of the engine code is as follows:

• C – Command series
• H – Horizontal PTO shaft
• 740 – Numerical designation

General information

Engine Specifications
Model	Command PRO CH740
Type	4-stroke, OHV, V-twin
Displacement	725 cm 3 (44.2 cu-in)
Max. horsepower	27.3 PS (20.1 kW; 27.0 HP) at 3,600 rpm 25.3 PS (18.6 kW; 25.0 HP) at 3,600 rpm
Max. torque	57.3 N·m (5.8 kg·m; 42.3 ft·lb) at 3,000 rpm 53.1 N·m (5.4 kg·m, 39.1 ft·lb) at 3,000 rpm
Fuel system	Carburetor with a fixed main jet (Nikki or Keihin)
Cooling system	Forced-air
Ignition system	CDI/MDI, ASAM/DSAM, DSAI (Digital Spark Advance Ignition)
Lubricating system	Pressurized lubrication
Starting system	Electric starter
Fuel used	Unleaded 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 weight	43.0 kg (94.0 lbs)

Cylinder Block and Head

Cylinder block
Compression ratio:		9.0:1
Bore x Stroke		83.0 mm X 67.0 mm (3.27 x 2.64 in)
Sleeve internal diameter		82.988-83.013 mm (3.2672-3.2682 in)
Number of piston rings (compression / oil):		2 / 1
Piston style A
Thrust face outer diameter		82.949-82.967 mm (3.2656-3.2664 in)
Piston pin outer diameter		16.995-17.000 mm (0.6691-0.6693 in)
Ring-to-groove side clearance:	Top	0.025-0.048 mm (0.001-0.0019 in)
	Second	0.015-0.037 mm (0.0006-0.0015 in)
	Oil	0.026-0.176 mm (0.001-0.0069 in)
Ring end gap:	Top	0.250-0.560 mm (0.0098-0.022 in)
	Second	0.250-0.560 mm (0.0098-0.022 in)
Piston style B
Thrust face outer diameter		82.978 mm (3.2668 in)
Piston pin outer diameter		16.995-17.000 mm (0.6691-0.6693 in)
Ring-to-groove side clearance:	Top	0.030-0.070 mm (0.001-0.0026 in)
	Second	0.030-0.070 mm (0.001-0.0026 in)
	Oil	0.060-0.190 mm (0.0022-0.0073 in)
Ring end gap:	Top	0.189-0.277 mm (0.0074-0.0109 in)
	Second	1.519-1.797 mm (0.0598-0.0708 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:	INTAKE	33.370-33.630 mm (1.3138-1.324 in)
	EXHAUST	29.370-29.630 mm (1.1563-1.1665 in)
Stem outer diameter:	INTAKE	6.982-7.000 mm (0.2749-0.2756 in)
	EXHAUST	6.970-6.988 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)
Flywheel	66.4 Nm (6.77 kg·m; 49 ft·lb)
Spark plug	27 Nm (2.75 kg·m; 20.0 ft·lb)

Service Information

Oil system
Oil type	API SG, SH, SJ, or higher
Recommended oil	SAE 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 plug	Champion RC12YC
Spark plug gap	0.76 mm (0.030 in)
Ignition module air gap	0.280-0.330 mm (0.011-0.013 in)