Motorcycle Glossary of Terms
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Rack-and-pinion - A pinion
gear on the end of a shaft that mates with
a rack. Sometimes used in clutch operating
Radial play - Up and down
movement about a shaft.
Radial ply tyres - Tyre
piles fun accross the tyre (from bead to bead)
and around the circumference of the tyre.
Less resistent to tread distortion than other
Radiator - A liquid-to-air
heat transfer device designed to reduce the
temperature of the coolant in a liquid-cooled
Rake - A feature of steering
geometry - the angle of the steering head
in relation to the vertical.
Rat bike - A motorcycle
not necessarily kept in pristine condition,
often painted matt black. Minimal maintenance
and mismatched parts often used.
Rear sets - Racing-style
footpegs, an aftermarket product designed
for racing. Allows the rider multiple riding
positions as they are adjustable.
Rebore - Providing a new
working surface to the cylinder bore by boring
out the old surface. Necessitates the use
of oversize piston and rings.
Rebound damping - A means
of controling the oscillation of a suspension
unit spring after it has been compressed.
Resists the spring's natural tendency to bounce
back after being compressed.
Rectifier - Device for converting
the ac output of an alernator into dc for
Red line - The maximum number
of revolutions per minute an engine can run
before damage occurs. Typically indicated
on the rev counter.
Reed valve - An induction
system commonly used on two-stroke engines.
Regulator - Device for mainitaining
the charging voltage from the generator or
alternator within a specified range.
Relay - An electrical device
used to switch heavy current on and off by
using a low current auxillary circuit.
Resistance - Measured in
ohms. An electrical component's ability to
pass electrical current.
Rev counter - displays the
amount of revs per minute (rpm).
Road rash - a term used
to describe the injury to a person's skin
when a rider falls or slides along the road,
hence the importance of using adequate protection
Rotary - Ccommon term for
a Wankel engined motorcycle.
Rotary valve - A valve driven
from the camshaft for inlet or exhaust and
usually a disc or cylinder shape. For either
2 or 4-stroke engines.
rpm - Revolutions per minute
Rubber - tyres.