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| A - D E - H I - L M - P
Q - T U - Z |
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Upside-Down Forks
Telescopic forks that are installed inverted compared to typical
forks. In this case the slider tubes are at the bottom and the heavier bodies are
at the top. This decreases the unsprung weight of the motorcycle and improves its
handling. Also known as inverted telescopic forks. |
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Valves (Intake and Exhaust)
Poppet valves within a four-stroke cylinder head that open and close
to allow fuel/air into the combustion chamber, and open and close to vent the burned
gas. Four-valve cylinder heads can more efficiently pump fuel/air in and pump spent
gas out, increasing performance.
V-Twin
Two-cylinder engine layout in which the cylinders form a “V.” |
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Water Cooling
Also known as “liquid cooling,” this system includes a radiator
and fluid to dissipate heat. Liquid is constantly circulated between the radiator
and motorcycle engine cylinders when the engine is operating. A small fan (controlled
by a thermostat) has a cooling effect on the liquid passing through the radiator.
Water-cooled bikes are less likely to overheat, compared to air cooled engines,
especially when traffic may be slow or jammed, which minimizes the heat transfer
of rapid air circulation that air cooling provides.
Wet Clutch
A clutch that contains many plates that are in the oil spray of the
transmission and the oil gets between the plates. The plates on wet clutches have
a tendency to stick together when the bike sits. So, when you start the bike in
the morning, before you put it in first gear to move off, depress the clutch lever
for about 30 seconds to allow the oil on the plates to drain off and the plates
to separate. Otherwise, you’ll get a decided clunk and slight movement forward when
you put it in first.
Wet Sump
As part of the lubricating system of an internal combustion engine, a wet
sump is a built-in oil reservoir at the base of the engine. From there oil is pumped
into various engine bearings and then drained back down to the sump.
A benefit of a wet sump, as compared to a dry sump, is its simple internal
design, using a single pump with no external reservoir or connecting hoses or tubes
which may leak. On the other hand a wet sump is unsuitable for high-perfomance applications,
such as racing through corners, where the oil may slosh around inside the sump and
briefly deprive the system of oil which could damage the engine.
Wheelbase
The horizontal distance between the ground contact points of the front and
rear wheels. Wheelbase is a function of motorcycle frame length, steering axis angle,
and fork offset. Wheelbase has a major influence on the longitudinal stability of
a bike (along with the height of the center of gravity). Short bikes are much more
likely to perform wheelies and stoppies and have the quickest handling characteristics.
On the other hand, a motorcycle’s straight-line stability improves with longer wheelbase.
For example, sport bikes have a shorter wheelbase and tourers have longer wheelbases.
Wheelie
An act of raising the front wheel of a motorcycle off the ground and keeping
it in the air while continuing to ride the bike. |
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