Kohler CH740NG

Kohler CH740NGThe Kohler CH740NG is a 725 cc (44.24 cu·in) natural aspirated V-twin four-stroke air-cooled internal combustion small propane/natural gas 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 CH740NG engine a total of 725 cc of displacement. The compression ratio rating is 9.0:1.

The CH740NG engine produced 19.7 PS (14.5 KW; 19.5 HP) at 3,600 rpm of maximum horsepower and 41.8 Nm (4.3 kg·m; 30.8 ft·lb) at 3,000 rpm of maximum torque.

The Kohler CH740NG features:

  • OHV design
  • Hydraulic valve lifters
  • Aluminum cylinder block
  • Cast iron cylinder liners
  • Hardened crank journals
  • PTO side-load sleeve bearing
  • Electronic ignition system
  • LPG/NG carburetor (IMPCO or Nikki)
  • Mechanical centrifugal governor
  • Full pressure lubrication system
  • Forced air cooling system
  • Electric starter

General information

Engine Specifications
Engine modelCommand PRO CH740NG
Engine type4-stroke, OHV, V-twin
Displacement725 cm3, (44.24 cu·in)
Max. horsepower19.7 PS (14.5 KW; 19.5 HP) at 3,600 rpm
Max. torque41.8 Nm (4.3 kg·m; 30.8 ft·lb) at 3,000 rpm
Cooling systemForced air
Air cleanerReplaceable, paper element
Lubricating systemFull pressure
Ignition systemElectronic ignition system
Fuel systemLPG/NG carburetor (IMPCO or Nikki)
Fuel usedPropane/natural gas
Starting systemElectric starter
GovernorMechanical centrifugal governor
PTO shaft rotationCounterclockwise (from PTO shaft side)
Dimensions (L x W X H)355 x 451 x 483 mm (14.0 x 17.7 x 19.0 in)
Dry weight43.0 kg (94.0 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)
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)
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)
Carburetor mounting nut6.2-7.3 Nm (0.63-0.74 kg·m; 4.6-5.4 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)
Ignition system
Type:Electronic ignition system
Spark plug:Champion RC12YC
Spark plug torque: Liquid propane: 0.76 mm (0.030 in)
Natural gas: 0.51 mm (0.020 in)
Ignition coil air gap0.280-0.330 mm (0.011-0.013 in)


1. Kohler Command CH18, CH20, CH23, CH25, CH640, CH730, CH740 Liquefied Petroleum Gas (LPG) or LPG/Natural Gas (NG) fueled 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.

ATTENTION! Dear visitors, this is an informational database of technical specifications, we are not a parts supplier or a marketplace.

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.

Be the first to comment

Leave a Reply

Your email address will not be published.