The Zongshen GB420S is a 420 cc, (25.63 cu·in) single-cylinder air-cooled 4-stroke internal combustion small gasoline engine, from GB-series manufactured by Zongshen Power Co. for general-purpose applications.
The Zongshen GB420S engine has an overhead valve (OHV) design, carburetor fuel system, transistorized ignition system, and recoil or electric starter.
Cylinder bore and piston stroke are 90.0 mm (3.54 in) and 66.0 mm (2.6 in), respectively. The ZS GB420S produced 12.2 PS (9.0 kW; 12.1 HP) at 3,600 rpm of maximum output power and 27 N·m (2.8 kg·m, 19.9 ft·lb) of maximum torque.
|Type||4-stroke, OHV, single cylinder|
|Displacement||420 cm2, (25.63 cu·in)|
|Max. horsepower||12.2 PS (9.0 kW; 12.1 HP) at 3,600 rpm|
|Max. torque||27 N·m (2.8 kg·m, 19.9 ft·lb)|
|Lubricating system||Splash system|
|Starting system||Recoil or electric starter|
|Fuel tank capacity||7.5 L (1.98 US. gal. 1.65 Imp. gal.)|
|PTO shaft rotation||Counterclockwise (from PTO shaft side)|
Dimensions and Weight
|Length, mm (in)||456 (18.0)|
|Width, mm (in)||355 (14.0)|
|Height, mm (in)||459 (18.1)|
|Dry weight, kg (lb)||30.5 kg (67.2 lbs)|
|Maximum speed:||3,600 rpm|
|Idle speed:||1,600±150 rpm|
|Oil type||4-stroke engines oil|
|Oil capacity||1.1 L (1.16 US. qt, 0.97 Imp. qt.)|
|Spark plug gap||0.6-0.8 mm (0.024-0.031 in)|
|Spark plug torque||20 N·m; 2.0 kg·m; 14.7 ft·lb|