| Engine Specifications | |
| Model | GX670 |
| Type | 4-stroke, OHV, 90° V-twin |
| Displacement | 670 cm 3 (40.9 cu-in) |
| Max. horsepower | 24 HP (17.7 kW HP) at 3,600 rpm |
| Max. torque (crank PTO) | 50.8 N·m (5.18 kg·m, 37.5 ft·lb) at 2,500 rpm |
| Carburetor | Horizontal type, butterfly valve |
| Cooling system | Forced-air |
| Ignition system | Transistorized magneto ignition |
| Lubricating system | Forced lubrication |
| Starting system | Electric starter |
| Stoping system | Ignition primary circuit ground |
| Fuel used | Unleaded gasoline (octane number 86 or higher) |
| Fuel consumption | 265 g/HPh |
| PTO shaft rotation | Counterclockwise (from PTO shaft side) |
| Cylinder block | ||
| Compression ratio: | 8.3:1 | |
| Bore x Stroke | 77 X 72 mm (3.0 x 2.8 in) | |
| Sleeve internal diameter | 77.00 mm (3.03 in) | |
| Piston skirt outer diameter | 76.985 mm (3.03 in) | |
| Cylinder Head | ||
| Warpage (limit) | 0.10 mm (0.004 in) | |
| Valve Arrangement: | OHV | |
| Valves: | 4 (2 per cylinder) | |
| Tightening torque specs | |
| Connecting rod bolt | 12 Nm; 1.2 kg·m; 9 ft·lb |
| Cylinder head bolt | 34 Nm; 3.5 kg·m; 25 ft·lb |
| Socket bolt | 27 Nm; 2.7 kg·m; 20 ft·lb |
| Flywheel nut | 196 Nm; 20.0 kg·m; 145 ft·lb |
| Pivot bolt | 24 Nm; 2.4 kg·m; 17 ft·lb |
| Pivot adjusting nut | 10 Nm; 1.0 kg·m; 7 ft·lb |
| Cylinder head cover bolt | 9 Nm; 0.9 kg·m; 6.5 ft·lb |
| Oil level switch joint nut | 10 Nm; 1.0 kg·m; 7 ft·lb |
| Oil drain bolt | 39 Nm; 4.0 kg·m; 29 ft·lb |
| Standard torque values | |
| Bolt, nut (5 mm) | 5.5 Nm; 0.55 kg·m; 4.0 ft·lb |
| Bolt, nut (6 mm) | 10 Nm; 1.0 kg·m; 7 ft·lb |
| Bolt, nut (8 mm) | 22 Nm; 2.2 kg·m; 16 ft·lb |
| Bolt, nut (10 mm) | 34 Nm; 3.5 kg·m; 25 ft·lb |
| Bolt, nut (12 mm) | 54 Nm; 5.5 kg·m; 40 ft·lb |
| Engine | |
| Maximum speed | 3,850 ± 100 rpm |
| Idle speed | 1,400 ± 150 rpm |
| Cylinder compression | 6.0-8.0 kg/cm2 (85-114 psi) at 500 rpm |
| Valve clearance | |
| Intake valve clearance | 0.15±0.02 mm (0.006±0.001 in) |
| Exhaust valve clearance | 0.20±0.02 mm (0.008±0.001 in) |
| Oil system | |
| Oil type | Honda 4-stroke or an equivalent (SG or SF) |
| Recommended oil | SAE 10W-30 |
| Oil capacity | 1.90 L |
| Oil change interval | Every 6 month or 100 Hrs. |
| Ignition system | |
| Spark plug |
NGK: ZGR5A DENSO: J16CR-U |
| Spark plug gap | 0.7-0.8 mm (0.028-0.031 in) |
