News Releases 2002

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Power Products
April 22, 2002

Honda Releases the GX25-the World's Lightest 4-Stroke Engine

April 22, 2002-Today, Honda Motor Co., Ltd. announced the release of the new GX25 25cc displacement, 360°-inclinable 4-stroke engine. At 2.78kg, this engine is the lightest of its kind in the world*1, making it the ideal power source for a variety of hand-held power equipment. The GX25 will be available at Honda power equipment dealers throughout Japan from June 27. Honda will also be supplying the engine to other power equipment manufacturer's on an OEM basis.

The GX25 was developed to meet three design objectives: to be the lightest in the world; to be 360°-inclinable; and to provide outstanding environmental performance.

The engine employs the world's most compact*2 oil-immersed timing belt OHC configuration, making it possible to incorporate the valve train into the oil reservoir for substantial weight and volume savings. Honda's original rotary slinger pumping lubrication system ensures full oil lubrication no matter what the engine angle, allowing it to be continuously operated or stored in any position.

The GX25 offers superb environmental performance, achieving a top-class*3 ranking under American EPA (Environmental Protection Agency) Phase 2 regulations-the most stringent in the world. It also delivers an outstanding balance of all-round performance, with a power-to-weight ratio of 0.29kW/kg (among the highest in the hand-held, 4-stroke engine category), combined with low noise and low vibration, for efficient, carefree operation.
*1,2 As of April 2002
*3 EPA: Class I-A (under 65cc displacement) and Class IV (20cc~50cc displacement)

GX25 360°-inclinable 4-stroke engine

GX25 360°-inclinable 4-stroke engine

Annual projected sales nationwide: 155,000 units
Manufacturer's suggested retail price  (consumption tax not included): ¥30,000

Other Features of the GX25

Smooth starting and superb acceleration

  • Mechanical decompression results in a class-beating starter rope pull weight of just about 7 kgf-so light that anyone can start it with ease. A newly developed accelerator pump-equipped carburetor result in excellent acceleration immediately after startup on par with that of a 2-stroke.

High environmental performance

  • A Honda e-SPEC engine that achieves top-class*4 ranking in American EPA (Environmental Protection Agency) Phase 2 regulations-the most stringent in the world. *4EPA: Class I-A (under 65cc displacement) Achieves top-of-class fuel economy and oil consumption. Oil-immersed timing belt reduces mechanical noise. Lighter pistons and other parts create less vibration, resulting in less fatigue during hand-held operation.


  • The engine is designed to allow the cover to be removed by loosening a single bolt. The air cleaner cover can be removed and replaced with just one hand.


  • Full-cover construction reduces snagging on branches or other objects during operation. Designed with a low center of gravity and a shape that doesn't catch on the operator's elbow, for greater operability and maneuverability.
    New Power Red coloring heightns brand identity for Honda power products. The new color will be gradually introduced to all power product engines, starting with the release of products featuring the GX25.


Model Name GX25
Type e-SPEC air-cooled 4-stroke single-cylinder OHC
Displacement(cm3) 25
L x W x H (mm) 192×221×230
Outfitted Weight (kg) 3.25
Dry Weight (kg) 2.78
No. of Cylinders / Bore x Stroke (mm) 1/35×26
Max. Power [kW (PS)/rpm] 0.81(1.1)/7,000
Max. Torque [N•m (kg•m)] 1.25(0.13)/5,000
Direction of Rotation Counterclockwise (viewed from output shaft side)
Fuel Type Automotive-grade unleaded gasoline
Fuel Tank Capacity (L) 0.55
Fuel Consumption (g/kW-h [g/PS-h]) 340(250)
Oil Reservoir Capacity (L) 0.08
Carburetor Diaphragm type (overflow return)
Ignition Transistorized magneto
Spark Plug NGK CM5H/CMR5H
Starter Recoil type