The Kohler CH12.5/CH12.5S is a 398 cc (24.3 cu·in) single-cylinder air-cooled four-stroke internal combustion gasoline engine from the Command PRO series, manufactured by Kohler Co.
The Kohler CH12.5 engine has an OHV (overhead valve) design, an aluminum block with cast iron cylinder liners, a horizontal PTO-shaft, full-pressurized lubrication system. This engine is equipped with a carburetor (Nikki or Keihin) with a fixed main jet and dependable electronic magneto ignition system.
A 87.0 mm (3.43 in) cylinder bore and 67.0 mm (2.64 in) piston stroke give the CH12.5 engine a total of 398 cc of displacement. The compression ratio rating is 8.5:1.
This engine produced 12.7 PS (9.33 KW; 12.5 HP) at 3,600 rpm of horsepower and 27.8 Nm (2.8 kg·m; 20.5 ft·lb) at 2,500 rpm of torque.
The breakdown of the engine code is as follows:
- C – Command series
- H – Horizontal PTO shaft
- 12.5 – Numerical designation
- Version code:
- S – Electric start
- T – Retractable start
- ST – Electric/Retractable start
- GT – Generator application/Retractable start
- GS – Generator application/Electric start
- PT – Pump/Retractable start
- RT – Gear reduction/Retractable start
General information
| Engine Specifications | |
| Model | Command PRO CH12.5 / CH12.5S |
| Type | 4-stroke, OHV, single-cylinder |
| Displacement | 398 cm 3 (24.3 cu-in) |
| Max. horsepower | 12.7 PS (9.33 KW; 12.5 HP) at 3,600 rpm |
| Max. torque | 27.8 Nm (2.8 kg·m; 20.5 ft·lb) at 2,500 rpm |
| Fuel system | Carburetor with a fixed main jet (Nikki or Keihin) |
| Cooling system | Forced-air |
| Ignition system | Dependable electronic magneto |
| Lubricating system | Pressurized lubrication |
| Starting system | Electric starter |
| Fuel used | Unleaded gasoline (octane number 86 or higher) |
| Dimensions (L x W X H) | 340 x 502 x 449 mm (13.41 x 19.8 x 17.7 in) |
| Dry weight | 39.5 kg (87.1 lbs) |
Cylinder Block and Head
| Cylinder block | ||
| Compression ratio: | 8.5:1 | |
| Bore x Stroke | 87.0 mm X 67.0 mm (3.43 x 2.64 in) | |
| Sleeve internal diameter | 87.000-87.025 mm (3.4252-3.4262 in) | |
| Number of piston rings (compression / oil): | 2 / 1 | |
| Thrust face outer diameter | 86.941-86.959 mm (3.4229-3.4236 in) | |
| Piston pin outer diameter | 18.995-19.000 mm (0.7478-0.748 in) | |
| Ring-to-groove side clearance: | Top | 0.040-0.105 mm (0.0016-0.0041 in) |
| Second | 0.040-0.072 mm (0.0016-0.0028 in) | |
| Oil | 0.551-0.675 mm (0.0217-0.0266 in) | |
| Ring end gap: | Top | 0.300-0.500 mm (0.0120-0.0197 in) |
| Second | 0.300-0.500 mm (0.0120-0.0197 in) | |
| Crankshaft main journal diameter: |
Flywheel end: 44.913-44.935 mm (1.7682-1.7691 in) Oil pan end: 41.915-41.935 mm (1.6502-1.6510 in) |
|
| Crankpin journal diameter: | 38.958-30.970 mm (1.5338-1.2193 in) | |
| Cylinder Head | ||
| Valve Arrangement: | OHV, gear drive | |
| Valves: | 2 | |
| Valve head diameter: | INTAKE | 35.370-35.630 mm (1.3925-1.4028 in) |
| EXHAUST | 31.370-31.630 mm (1.235-1.2453 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 (torque in 2 increments) |
Step 1: 20.0 Nm (2.0 kg·m; 15.0 ft·lb) Step 2: 40.0 Nm (4.0 kg·m; 30.0 ft·lb) |
| Flywheel | 66.4 Nm (6.77 kg·m; 49 ft·lb) |
| Spark plug | 38.0-43.4 Nm (3.9-4.4 kgf·m; 28.0-32.0 lb·ft) |
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 | 1.00 mm (0.0394 in) |
| Ignition module air gap | 0.200-0.300 mm (0.0079-0.0118 in) |
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