The GY6 engine design is a

four-stroke A four-stroke (also four-cycle) engine is an internal combustion (IC) engine in which the piston completes four separate strokes while turning the crankshaft. A stroke refers to the full travel of the piston along the cylinder, in either directio ...

single-cylinder A single-cylinder engine, sometimes called a thumper, is a piston engine with one cylinder. This engine is often used for motorcycles, motor scooters, motorized bicycles, go-karts, all-terrain vehicles, radio-controlled vehicles, power tools an ...

in a near-horizontal orientation that is used on a number of small

motorcycle A motorcycle (motorbike, bike; uni (if one-wheeled); trike (if three-wheeled); quad (if four-wheeled)) is a lightweight private 1-to-2 passenger personal motor vehicle Steering, steered by a Motorcycle handlebar, handlebar from a saddle-style ...

s or scooters made in Taiwan, China, and other southeast Asian countries. It has since become a generic technology. Kymco went on to produce

Honda commonly known as just Honda, is a Japanese multinational corporation, multinational Conglomerate (company), conglomerate automotive manufacturer headquartered in Minato, Tokyo, Japan. Founded in October 1946 by Soichiro Honda, Honda has bee ...

clones such as the Pulsar (CB125), made to Honda standards, as part of their range. Honda's KCW125 (the commercial name in Japan is "Spacy") was modified by Taiwan's Kwang Yang Motor Co., Ltd. (KYMCO), under Honda's consultancy, and became a standard model called the GY6, which various Taiwan makers imitated and minor-changed. Apparently, vehicles of this model were imported from Taiwan by various manufacturers and traders, and spread mainly in the southern coastal regions of China.

Configuration

The GY6 single is forced-air-cooled, with a chain-driven

overhead camshaft An overhead camshaft (OHC) engine is a piston engine in which the camshaft is located in the cylinder head above the combustion chamber. This contrasts with earlier overhead valve engines (OHV), where the camshaft is located below the combustio ...

and a crossflow

hemi Hemi may refer to: People Surname * Jack Hemi (1914–1996), New Zealand freezing worker, rugby union and league player, shearer * Ronald Hemi (1933–2000), New Zealand rugby union player Given name * Hemi Bawa, Indian painter and sculptor * ...

cylinder head In a piston engine, the cylinder head sits above the cylinders, forming the roof of the combustion chamber. In sidevalve engines the head is a simple plate of metal containing the spark plugs and possibly heat dissipation fins. In more modern ...

. Fuel metering is by a single constant-velocity style sidedraft

carburetor A carburetor (also spelled carburettor or carburetter) is a device used by a gasoline internal combustion engine to control and mix air and fuel entering the engine. The primary method of adding fuel to the intake air is through the Ventu ...

, typically a Keihin CVK clone or similar. Ignition is by

capacitor discharge ignition Capacitor discharge ignition (CDI) or thyristor ignition is a type of automotive electronic ignition system which is widely used in outboard motors, motorcycles, lawn mowers, chainsaws, small engines, gas turbine-powered aircraft, and some cars ...

(CDI), with a magnetic trigger on the flywheel. Because the trigger is on the flywheel instead of the camshaft, the ignition will fire on both the compression and exhaust strokes, making it a wasted spark ignition. An integrated magneto provides 50 V AC power for the CDI system and 20-30 V AC rectified and regulated to 12 V DC for chassis accessories such as lighting and to charge a battery. It includes an integrated

swingarm A swingarm ( or swinging arm), originally known as a swing fork or pivoted fork, is a single or double sided mechanical device which attaches the rear wheel of a motorcycle to its body, allowing it to pivot vertically. The main component of the ...

, which houses a centrifugally-controlled

continuously variable transmission A continuously variable transmission (CVT) is an automated Transmission (mechanical device), transmission that can change through a continuous range of gear ratios, typically resulting in better fuel economy in gasoline applications. This contr ...

(CVT) using a rubber belt sometimes called a VDP. At the rear of the swingarm, a

centrifugal clutch A centrifugal clutch is an automatic clutch that uses centrifugal force to operate. The output shaft is disengaged at lower rotational speed and engages as the output increases to a certain speed. It is often used in mopeds, underbones, lawn mower ...

connects the transmission to a simple integral gear-reduction unit. There is no clutch of any kind between the CVT and the crankshaft; it is engaged via a

at the rear pulley in the same fashion as

Vespa Vespa () is an Italian brand of scooters and mopeds manufactured by Piaggio. The name means wasp in Italian. The Vespa has evolved from a single model motor scooter manufactured in 1946 by Piaggio & Co. S.p.A. of Pontedera, Italy, to a ...

Grande, Bravo, and variated

Ciao ( , ) is an informal salutation in the Italian language that is used for both " hello" and "goodbye". Originally from the Venetian language, it has entered the vocabulary of English and of many other languages around the world. Its dual mea ...

model, as well as Honda Camino/Hobbit scooters/

mopeds A moped ( ) is a type of small motorcycle, generally having a less stringent licensing requirement than full motorcycles or automobiles. Historically, the term exclusively meant a similar vehicle with both bicycle pedals and a motorcycle engine. ...

. The engine produced around 20hp and 32nm of torque. An electric starter, backup kick-starter, and rear brake hardware is also housed in the swingarm.

Configuration

References

Further reading