Background and Identification
The Honda General Purpose Engine GX25 is the smaller sibling of the GX35 Honda engine. The GX25 is a 25.0cc, four-stroke, single-cylinder, overhead camshaft engine that produces approximately 1-horsepower at 7000 revolutions per minute. The GX35 is slightly more powerful and produces 1.3-horsepower with a displacement of 35.8cc. The belt-driven overhead camshaft reduces the engine’s mechanical noise output. When the GX25 was released, it was the world’s lightest overhead camshaft engine, according to Honda. Separate configurations of the GX25 engine are available for horizontal and vertical applications.
The GX25 engine includes a digital CDI (capacitor discharge ignition) that is designed specifically for use with small tillers. The engine has an easily accessible spark plug that can be replaced. This engine does not require the user to mix gasoline and oil. The engine can hold 2.7 ounces of oil and 0.61 quarts of fuel. Honda recommends using unleaded 86 octane or higher gasoline for this engine. The GX35 engine, in comparison, holds up to 2.7 fluid ounces of oil and 0.67 quarts of fuel.
The GX25 model is “CARB compliant” and “EPA compliant,” meaning that the engine meets the California Air Resources Board’s and Environmental Protection Agency’s rules and regulations for air pollution.
The Honda General Purpose Engine GX25 can be identified by the name “GX25” above the brand name “Honda” in capital letters on the back cover of the engine. The GX25 has a red main engine cover and black details.
Engine type: 4-stroke single cylinder OHC petrol engine
Bore x Stroke: 35 x 26 mm
Displacement: 25.0 cm³
Compression ratio: 8.0 : 1
Net power: 0.7 kW ( 1.0 HP ) / 7000 rpm
Max. net torque: 1.0 Nm ( 0.10 kgfm ) / 5000 rpm
Ignition system: Transistorised
Fuel tank capacity: 0.58 Liter
Fuel cons. at net power: 0.54 L/h 7000 rpm
Lubrication: Oil mist
Engine oil capacity: 0.08 Liter
Dimensions (L x W x H): 192 x 221 x 230 mm
Dry weight: 2.78 kg