The Kohler KT620 is a 660 cc, (40.3 cu·in) V-twin air-cooled four-stroke internal combustion gasoline engine from the 6600 series, manufactured by Kohler Co.
The Kohler KT620 engine has an OHV (overhead valve) design, an aluminum block with cast iron cylinder liners, vertical PTO-shaft, pressurized lubrication system. This engine is equipped with a electronic ignition system and carburetor with fixed main jet (Keihin or Walbro).
The cylinder bore and the piston stroke are 83.0 mm (3.27 in) and 61.0 mm (2.40 in), respectively. Compression ratio rating is 9.1:1.
The KT620 engine produced 21.4 PS (15.7 KW; 21.0 HP) at 3,600 rpm of horsepower and 48.7 Nm (5.0 kg·m; 36.0 ft·lb) at 2,200 rpm of torque.
The breakdown of the engine code is as follows:
- KT – 6600 series
- 620 – Numerical designation
General information
| Engine Specifications | |
| Model | KT620 |
| Type | 4-stroke, OHV, V-twin |
| Displacement | 660 cm 3 (40.3 cu-in) |
| Max. horsepower | 21.4 PS (15.7 KW; 21.0 HP) at 3,600 rpm |
| Max. torque | 48.7 Nm (5.0 kg·m; 36.0 ft·lb) at 2,200 rpm |
| Fuel system | Carburetor with fixed main jet (Keihin or Walbro) |
| Cooling system | Forced-air |
| Ignition system | Electronic ignition system |
| Lubricating system | Pressurized lubrication |
| Starting system | Electric starter |
| Fuel used | Unleaded gasoline (octane number 86 or higher) |
| Dimensions (L x W X H) | 473 x 424 x 341 mm (18.6 x 16.7 x 13.4 in) |
| Dry weight | 37.2 kg (82.0 lbs) |
Cylinder Block and Head
| Cylinder block | ||
| Compression ratio: | 9.1:1 | |
| Bore x Stroke | 83.0 mm X 61.0 mm (3.27 x 2.40 in) | |
| Sleeve internal diameter | 83.006-83.031 mm (3.2679-3.2689 in) | |
| Thrust face outer diameter | 82.978 mm (3.2668 in) | |
| Number of piston rings (compression / oil): | 2 / 1 | |
| 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: | 35.950-35.974 mm (1.4154-1.4163 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 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) |
| Rocker arm stud | 11.3 Nm (1.2 kgf·m; 8.3 ft·lb) |
| Connecting rod cap |
Black Coating 11.3 Nm (1.2 kgf·m; 8.3 ft·lb) Gray Metallic Coating 13.6 Nm (1.4 kgf·m; 10.0 ft·lb) |
| Flywheel retaining screw | 74.5 Nm (7.6 kgf·m; 55.0 ft·lb) |
| Governor lever nut | 6.8 Nm (0.7 kgf·m; 5.0 ft·lb) |
| Spark plug | 27.0 Nm (2.75 kg·m; 20.0 ft·lb) |
Service Information
| Valve clearance | |
| Intake | 0.101-0.152 mm (0.004-0.006 in) |
| Exhaust | 0.101-0.152 mm (0.004-0.006 in) |
| 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 | 0.203-0.305 mm (0.008-0.012 in) |
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