Kohler CH745

Kohler CH745The Kohler CH745 is a 725 cc (44.24 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 67.0 mm (2.64 in) piston stroke give the CH745 engine a total of 725 cc of displacement. The compression ratio rating is 9.0:1.

The CH745 engine produced 28.4 PS (20.9 KW; 28.0 HP) at 3,600 rpm of maximum horsepower and 57.9 Nm (5.9 kg·m; 42.7 ft·lb) at 2,600 rpm of maximum torque.

The Kohler CH745 features:

  • OHV (overhead valve) design
  • Hydraulic valve lifters
  • Aluminum cylinder block
  • Cast iron cylinder liners
  • Hardened crank journals
  • PTO thrust bearing
  • Electronic ignition system
  • Electronic fuel injection system (EFI)
  • Full pressure lubrication system
  • Oil cooler
  • Spin-on, full-flow oil filter
  • Forced air cooling system
  • Solenoid shift starter
  • 20 amp charging, regulated

General information

Engine Specifications
Engine modelCommand PRO CH745
Engine type4-stroke, OHV, V-twin
Displacement725 cm3, (44.24 cu·in)
Max. horsepower28.4 PS (20.9 KW; 28.0 HP) at 3,600 rpm
Max. torque57.9 Nm (5.9 kg·m; 42.7 ft·lb) at 2,600 rpm
Cooling systemForced air
Air cleanerReplaceable, paper element
Lubricating systemFull pressure
Ignition systemElectronic ignition system
Fuel systemElectronic fuel injection system (EFI)
Fuel usedUnleaded gasoline (octane number 86 or higher)
Starting systemElectric starter
Charging system20-amp charging, regulated
GovernorMechanical centrifugal governor
PTO shaft rotationCounterclockwise (from PTO shaft side)
Dimensions (L x W X H)355 x 451 x 673 mm (14.0 x 17.7 x 26.5 in)
Dry weight43.0 kg (94.8 lbs)

Cylinder Block and Head

Cylinder block
Compression ratio:9.0:1
Cylinder bore:83.0 mm (3.27 in)
Piston stroke:67.0 mm (2.64 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)
Piston style A
Thrust face outer diameter (standard):82.949-82.967 mm (3.2656-3.2664 in)
Side clearance (Top):0.025-0.048 mm (0.001-0.0019 in)
Side clearance (Second):0.015-0.037 mm (0.0006-0.0015 in)
Side clearance (Oil):0.026-0.176 mm (0.001-0.0069 in)
Ring end gap (Top):0.25-0.560 mm (0.0098-0.022 in)
Ring end gap (Second):0.25-0.560 mm (0.0098-0.022 in)
Piston style B
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)
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)
Crankshaft center distance:33.5 mm (1.32 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 8 mm straight shank: 22.7 Nm (2.32 kg·m; 16.75 ft·lb)
8 mm step-down: 14.7 Nm (1.5 kg·m; 10.85 ft·lb)
6 mm straight shank: 11.3 Nm (1.15 kg·m; 8.34 ft·lb)
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)
Oil drain plug13.6 Nm (1.4 kg·m; 10.0 ft·lb)

Service Data

Maximum speed:3600±50 rpm
Idle speed:1200±75 rpm
Compression pressure
Standard:1.1 MPa (160 psi)
Compression differential limit between cylinders:15% and less
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:Carburetor with fixed main jet (Nikki or Keihin)
Fuel pump:Pulse type
Fuel filter:In-line
Main fuel:2-1/2 turns
Idle fuel:3/4 to 1 full turn
Ignition system
Type:Fixed ignition or Smart-Spark advance
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)


1. Kohler Command PRO EFI ECH630-ECH749, CH735, CH26, CH745 service manual. Kohler Co. 2023.

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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