About GY6 Engines & Components

What is a GY6?
The Honda Motor company has been said to have perfected the scooter engine design in the 1960s. Building upon that technology a newer motor, the Honda gy6 engine, was produced in the 1980s. This is a 4 stroke single cylinder, air or oil cooled design that comes standard with two overhead valves. Stock horsepower ratings can be found quoted in the range of 7.8 hp (5.8 kW) to 12.4 hp (9.2 kW). The engine is capable of producing 12,000 rpm and power upwards of 14 horsepower (10 kW) with modifications according to end users. The GY6 engine has a built in swing arm with automatic CVT transmission that is belt driven. This engine was originally manufactured in 50 cc (3.1), 125 cc (7.6 cu in), and 150 cc (9.2 cu in) engine sizes and was found in the Honda Elite and Spacey line of motor scooters. Honda no longer uses this design on their scooters, but Chinese, Korean, and Taiwanese copies of this engine are readily available. Current brands of import scooter lines that use the Honda GY6 cloned engine technology include: Kymco, PGO (imported by Genuine Scooter Company in the USA), Ricardo Motors, Roketa, Strada, SUNL, Tank, Vento, Yamati, and many others.

How do I know if I have a GY6?
If you look just under the left side engine cover, right above the kick stand, there will be a series of
engraved letters and numbers. If you see QMB139, then you have a 50cc GY6, if you see QMJ157, then you have a 150cc GY6 engine

What is a CVT transmission?
Peer into a planetary automatic transmission, and you'll see a complex world of gears, brakes, clutches and governing devices. By comparison, a continuously variable transmission is a study in simplicity. Most CVTs only have three basic components:

• A high-power metal or rubber belt
• A variable-input "driving" pulley
• An output "driven" pulley

The variable-diameter pulleys are the heart of a CVT. Each pulley is made of two 20-degree cones facing each other. A belt rides in the groove between the two cones. V-belts are preferred if the belt is made of rubber. V-belts get their name from the fact that the belts bear a V-shaped cross section, which increases the frictional grip of the belt.
When the two cones of the pulley are far apart (when the diameter increases), the belt rides lower in the groove, and the radius of the belt loop going around the pulley gets smaller. When the cones are close together (when the diameter decreases), the belt rides higher in the groove, and the radius of the belt loop going around the pulley gets larger. CVTs may use hydraulic pressure, centrifugal force or spring tension to create the force necessary to adjust the pulley halves.
Variable-diameter pulleys must always come in pairs. One of the pulleys, known as the drive pulley (variator), is connected to the crankshaft of the engine. The driving pulley is also called the input pulley because it's where the energy from the engine enters the transmission. The second pulley is called the driven pulley because the first pulley is turning it. As an output pulley, the driven pulley transfers energy to the drive shaft.
When one pulley increases its radius, the other decreases its radius to keep the belt tight. As the two pulleys change their radii relative to one another, they create an infinite number of gear ratios -- from low to high and everything in between. For example, when the pitch radius is small on the driving pulley and large on the driven pulley, then the rotational speed of the driven pulley decreases, resulting in a lower “gear.” When the pitch radius is large on the driving pulley and small on the driven pulley, then the rotational speed of the driven pulley increases, resulting in a higher “gear.” Thus, in theory, a CVT has an infinite number of "gears" that it can run through at any time, at any engine or vehicle speed.

What is an AC or DC CDI?
CDI modules can be generally divided into two:-