
The Rato RV670 engine has an OHV (overhead valve) design with 90° V-twin cylinders; flat suction valve carburetor; recoil starter or electric starter, Inductance Discharge Type ignition system and centrifugal mechanical governor system.
The Rato RV670 motor has a 78.0 mm (3.07 in) cylinder bore and 70.0 mm (2.76 in) piston stroke with a compression ratio of 8.1:1. It produced 23.0 HP at 3,600 rpm of horsepower and 45 N·m (4.58 kg·m, 19.9 ft·lb) at 2,500 rpm of torque.
General information
| Engine Specifications | |
| Model | RV670 | 
| Type | 4-stroke, OHV, 90° V-twin | 
| Displacement | 670 cm 3 (40.9 cu-in) | 
| Max. horsepower | 23.0 HP at 3,600 rpm | 
| Max. torque (crank PTO) | 45 N·m (4.58 kg·m, 19.9 ft·lb) at 2,500 rpm | 
| Carburetor | Flat suction valve carburetor | 
| Cooling system | Forced-air | 
| Ignition system | Inductance Discharge Type | 
| Lubricating system | Splash | 
| Starting system | Recoil / electric starter | 
| Stoping system | Ignition primary circuit ground | 
| Fuel used | Unleaded gasoline (octane number 86 or higher) | 
| PTO shaft rotation | Counterclockwise (from PTO shaft side) | 
Service Information
| 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 | API 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) | 
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