Kohler CH742

Kohler CH742The Kohler CH742 is a 747 cc (45.6 cu·in) natural aspirated V-twin four-stroke air-cooled internal combustion small gasoline engine from the Command PRO series with a horizontal shaft, manufactured by Kohler Co for general-purpose applications.

A 83.0 mm (3.27 in) cylinder bore and 69.0 mm (2.72 in) piston stroke give the CH742 engine a total of 747 cc of displacement. The compression ratio rating is 9.1:1.

The CH742 engine produces 25.3 PS (18.6 KW; 25.0 HP) at 3,600 rpm of maximum horsepower and 55.9 Nm (5.7 kg·m; 41.2 ft·lb) at 2,600 rpm of peak torque.

The Kohler CH742 features:

  • OHV design
  • Hydraulic valve lifters
  • Aluminum cylinder block
  • Cast iron cylinder liners
  • Hardened crank journals
  • PTO side-load sleeve bearing
  • CDI or MDI ignition system
  • Two-barrel side-draft carburetor with fixed main jets (Walbro)
  • Mechanical centrifugal governor
  • Full pressure lubrication system
  • Forced air cooling system
  • Electric starter

General information

Engine Specifications
Engine modelCommand PRO CH742
Engine type4-stroke, OHV, V-twin
Displacement747 cm3, (45.6 cu·in)
Max. horsepower25.3 PS (18.6 KW; 25.0 HP) at 3,600 rpm
Max. torque55.9 Nm (5.7 kg·m; 41.2 ft·lb) at 2,600 rpm
Cooling systemForced air
Air cleanerHigh-efficiency, heavy-duty air filters
Lubricating systemFull pressure
Ignition systemFixed timing CDI or MDI ignition system
Fuel systemTwo-barrel side-draft carburetor with fixed main jets (Walbro)
Fuel usedUnleaded gasoline (octane number 86 or higher)
Starting systemElectric starter
GovernorMechanical centrifugal governor
PTO shaft rotationCounterclockwise (from PTO shaft side)
Dimensions (L x W X H)371 x 451 x 622 mm (14.6 x 17.7 x 24.5 in)
Dry weight48.0 kg (105.0 lbs)

Cylinder Block and Head

Cylinder block
Compression ratio:9.1:1
Cylinder bore:83.0 mm (3.27 in)
Piston stroke:69.0 mm (2.72 in)
Cylinder internal diameter (standard):82.988-83.013 mm (3.2672-3.2682 in)
Number of piston rings (compression / oil):2/1
Piston pin diameter:16.995-17.000 mm (0.6691-0.6693 in)
Thrust face outer diameter (standard):82.978 mm (3.2668 in)
Side clearance (Top):0.030-0.070 mm (0.0010-0.0026 in)
Side clearance (Second):0.030-0.070 mm (0.0010-0.0026 in)
Side clearance (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)
Ring end gap (Second):1.519-1.797 mm (0.0598-0.0708 in)
Crankshaft
Number of main bearings:2
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 driven
Valves:2 (4 valves in total)
Valve head diameter (INTAKE):33.370-33.630 mm (1.3138-1.324 in)
Valve head diameter (EXHAUST):29.370-29.630 mm (1.1563-1.1665 in)
Valve seat angle (INTAKE):89°
Valve seat angle (EXHAUST):89°
Valve seat angle (INTAKE):45°
Valve seat angle (EXHAUST):45°
Valve steam diameter (INTAKE):6.982-7.000 mm (0.2749-0.2756 in)
Valve steam diameter (EXHAUST):6.970-6.988 mm (0.2744-0.2751 in)
Valve lift minimal (INTAKE):8.07 mm (0.3177 in)
Valve lift minimal (EXHAUST):8.07 mm (0.3177 in)
Camshaft journal diameter :19.962-19.975 mm (0.7859-0.7864 in)

Tightening torque specs

Tightening torque specs
Intake manifold mounting (torque in 2 increments) Step 1: 7.4 Nm (0.75 kg·m; 5.5 ft·lb)
Step 2: 9.9 Nm (1.00 kg·m; 7.3 ft·lb)
Connecting rod cap fastener13.6 Nm (1.4 kgf·m; 10.0 lb·ft)
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)
Fan9.9 Nm (1.0 kg·m; 7.3 ft·lb)
Flywheel66.4 Nm (6.77 kg·m; 49.0 ft·lb)
Governor lever nut6.8 Nm (0.69 kg·m; 5.02 ft·lb)
Muffler retaining nuts24.4 Nm (2.5 kg·m; 18.0 ft·lb)
Spark plug27 Nm (2.75 kg·m; 20.0 ft·lb)

Service Data

Engine
Maximum speed:3600±50 rpm
Idle speed:1200±75 rpm
Oil system
Lubrication system:Full pressure
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)
Fuel system
Type:Two-barrel side-draft carburetor with fixed main jets (Walbro)
Fuel pump:Pulse type
Fuel filter:In-line
Ignition system
Type:Fixed timing CDI or MDI ignition system
Spark plug:Champion RC12YC
Spark plug gap:0.76 mm (0.030 in)
Ignition coil air gap0.280-0.330 mm (0.011-0.013 in)

References

1. Kohler Command CH682, CH732, CH742, CH752 service manual. Kohler Co. 2021.

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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We try to use official documentation and verify the published data, but errors may occur. In addition, specifications of machinery and equipment may vary depending on markets and modifications. We do not recommend the use of this data for spare parts or repairs. Use official service manuals or parts catalogs for your product.

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