Motorcycle Glossary of Terms
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Cafe racer - A style of
bike made popular in London in the 1950's
when bikes travelled from cafe to cafe.
Cam - Device for opening
and closing a valve.
Cam chain - The chain which
takes drive from the crankshaft to the camshaft(s).
Camshaft - The mounting
shaft for the cam, can be in low, high or
Carbon - A very lightweight
and rigid material used in aftermarked parts
to reduce weight, often used in racing. Improves
power to weight ratio and overall look of
Catalytic converter - A
device in the exhaust system of some machines
which converts certain pollutants in the exhaust
gases into less harmful substances.
Carburettor - Used to produce
the air-fuel mixture.
cc - Cubic Centimeter.
CDI - (Capacitor Discharge
Ignition) a computer controlled Ignition,
unit often reprogramable.
CE armour - A system of
European grading in motorcycle armour to reduce
the chances of being hurt in a motorcycle
accident. Compresses on impact.
Chain drive - Primary form
of drive from engine to gearbox and secondary
gearbox to rear wheel.
Charging system - Description
of the components which charge the battery,
ie the alternator, rectifier and regulator.
Chicane - A series of track
back-to-back left and right hand bends (or
Chopper - A motorcycle where
the non-essential parts have been removed.
Ofter applies to a custom-built motorcycle
that may have a rigid frame, extended forks
a stretched appearance and often no suspension.
CI - Cubic inch, mainly
used in America.
Circlip - A ring-shaped
clip used to prevent endwise movement of cylindrical
parts and shafts. An internal circlip is installed
in a groove in a housing; an external circlip
fits into a groove on the outside of a cylindrical
piece such as a shaft. Also know as a snap-ring.
Clearance - The amount of
space between a piston and a cylinder, between
a bearing and a journal, etc.
Clip-ons - Handlebars clamped
around the top of the fork tubes, lowering
a rider's position for maximum aerodynamics.
Close Ratio - normally found
on Racing gearbox.
Clutch - Mechanism that
disengages the engine from the wheels.
Coil spring - A spiral of
elastic steel found in various sizes throughout
a vehicle, for example as a springing medium
in the suspension and in the valve train.
Combustion chamber - Area
where the fuel/air mixture is compressed and
fired, between piston and cylinder head.
Compression - Reduction
in volume, and increase in pressure and temperature,
of a gas, caused by squeezing it into a smaller
Compression damping - Controls
the speed the suspension compresses when hitting
Compression ratio - The
fuel/air mixture compression degree.
Countersteering - The input
a rider gives to the handlebars in order to
Cp - Candlepower. Bulb rating
commonly found on US motorcycles.
Crankcase - The casing enclosing
the crankshaft and its attachments.
Crankshaft - The shaft for
converting the up-and down piston motion into
Crossply tyre - Tyre plies
arranged in a criss-cross pattern. Usually
four or six plies used, hence 4PR or 6PR in
tyre size codes.
Cruiser - Generally refers
to a motorcycle equipped with a low seat and
pullback handlebars, stemmed from the 1960's.
Cylinder - Containing the
piston and capped by the cylinder head, is
the site of the expansion which provides power.
Cylinder head - In a vertical
engine caps off the top end of the cylinder.
In a 4-stroke engine carries the valve.