The Kohler CH730 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 CH730 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 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 CH730 engine produced 23.8 PS (17.5 KW; 23.5 HP) at 3,600 rpm of horsepower and 52.1 Nm (5.3 kg·m; 38.4 ft·lb) at 2,800 rpm of torque, or 25.3 PS (18.6 kW; 25.0 HP) at 3,600 rpm of horsepower and 54.1 Nm (5.52 kg·m; 39.9 ft·lb) at 2,800 rpm, depending on the engine version.
The breakdown of the engine code is as follows:
- C – Command series
- H – Horizontal PTO shaft
- 730 – Numerical designation
General information
| Engine Specifications | |
| Model | Command PRO CH730 |
| Type | 4-stroke, OHV, V-twin |
| Displacement | 725 cm 3 (44.2 cu-in) |
| Max. horsepower |
23.8 PS (17.5 KW; 23.5 HP) at 3,600 rpm 25.3 PS (18.6 kW; 25.0 HP) at 3,600 rpm |
| Max. torque |
52.1 Nm (5.3 kg·m; 38.4 ft·lb) at 2,800 rpm 54.1 Nm (5.52 kg·m; 39.9 ft·lb) at 2,800 rpm |
| Fuel system | Carburetor with a fixed main jet (Nikki or Keihin) |
| Cooling system | Forced-air |
| Ignition system | CDI/MDI, ASAM/DSAM, DSAI |
| 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) |
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