Underbone

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Modern underbones use plastic cover sets, allowing users to customize their bikes easily such like this Modenas Kriss 2.

Underbones or Underbone Motorcycles are a class of small motorcycles (also know as mopeds in some country) that are halfway between true scooters and motorcycles. Underbones are popular in East Asian and South East Asian countries for their low cost yet reliable and fuel efficiency. They are referred to as kapchai in Malaysia.

1 Design
2 History
3 The origin of the word "kapchai"
4 Underbone Culture
5 See Also
6 References

[edit] Design

Underbones are usually built around a singular tube frame (the "underbone") that supports the whole bike^[1]. This frame usually runs low across the length of the bike providing for a step through similar to a scooters and giving the class its name. The engine is mounted under the frame (usually laid flat on its side) and uses the similar manual sequential transmission as used in bigger motorcycles, but with automatic centrifugal clutch. However, some underbones use manual clutches, especially performance models. Unlike true scooters, underbones still use a chain drive and are ridden like regular motorcycles (compared to scooters which in general utilize a feet forwards riding position).

Most underbones are still using carburetors for the fuel system, with the exception of Honda Wave 125i which uses fuel injection. While most motorcycles have their fuel tanks positioned at the top front part, the fuel tanks in underbones are located below the seats. All modern underbones use capacitor discharge ignition for the ignition system.

Underbones usually carry engines of about 50 cc to 125 cc with the largest displacement being 150cc for bikes such as the Suzuki Raider 150.

[edit] History

Underbones developed from early moped models introduced in the early 1950's, many of which were simply bicycles with motors attached. One of the first underbone like motorcycles was the Honda Cub and it was arguably the success of the Cub that brought about the modern underbone. However, it was later plastic bodied, tube frame mopeds like the Honda Wave that set the modern standards from which most, if not all underbones are drawn from today.

[edit] The origin of the word "kapchai"

The word "kapcai" or "kapchai" is originally a slang derived from Malaysian Cantonese and Hokkien, its origin is from the word Honda Cub. In Cantonese "Cai" means "little" or "Son". Therefore,"Kapcai" literally means a "Small Cub". Honda is a popular brand in Malaysia and as the result for this, all underbone motorbikes were called "kapcai".

[edit] Underbone Culture

In South East Asia where underbones are very popular, there exists a healthy market for aftermarket and tuner parts. Many enthusiaist modify their underbones either for show, installing small sound systems and neon lights and custom paint jobs, or for racing, inceasing the engine power and fine tuning the suspension. Illegal underbone drag racing has become popular in countries like the Philippines, this poses a problem as underbones offer little protection in the event of a crash. The most popular underbone for these purposes is the Honda XRM although similar models from Kawasaki and Yamaha are also frequently used.

Street racing culture among teenage underbone riders in Malaysia is now became serious, especially in large urban areas such as in Kuala Lumpur, Penang and Johor Bahru. The street racers who are known as Mat Rempit always ride in dangerous manner and they are famous with their Superman stunt and also their cilok antiques where they weave in-between the moving traffic at high speed. The Malaysian Police and Road Transport Department frequently launch operations to curb street racing.