The GY6 engine design is a four-stroke

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, go-karts, all-terrain vehicles, radio-controlled vehicles, portable tools and garden machinery ( ...

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

motorcycle A motorcycle (motorbike, bike, or trike (if three-wheeled)) is a two or three-wheeled motor vehicle steered by a handlebar. Motorcycle design varies greatly to suit a range of different purposes: long-distance travel, commuting, cruising ...

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 clones such as the Pulsar (CB125), made to Honda standards, as part of their range. 24- The four stroke engine for 125cc scooters. 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. Source link: https://ir.ide.go.jp/?action=repository_action_common_download&item_id=40179&item_no=1&attribute_id=26&file_no=1

Configuration

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

overhead camshaft An overhead camshaft (OHC) engine is a piston engine where 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 combustion cha ...

and a crossflow hemi

cylinder head In an internal combustion engine, the cylinder head (often abbreviated to simply "head") sits above the cylinders and forms the roof of the combustion chamber. In sidevalve engines, the head is a simple sheet of metal; whereas in more modern ...

. Fuel metering is by a single constant-velocity style sidedraft carburetor, 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, turbine-powered aircraft, and some cars. It ...

(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 A wasted spark system is a type of ignition system used in some four-stroke cycle internal combustion engines. In a wasted spark system, the spark plugs fire in pairs, with one plug in a cylinder on its compression stroke and the other plug in a ...

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, which houses a centrifugally controlled Continuously variable transmission (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 low rotational speed and engages more as speed increases. It is often used in mopeds, underbones, lawn mowers, go-karts, chainsaw ...

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 luxury 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 ...

Grande, Bravo and variated Ciao 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. The term used to mean a similar vehicle except with both bicycle pedals and a motorcycle engine. Mopeds typi ...

. An electric starter, backup kick-starter, and rear brake hardware is also housed in the swingarm.

References

https://ir.ide.go.jp/?action=repository_action_common_download&item_id=40179&item_no=1&attribute_id=26&file_no=1

Configuration

References

Further reading