Motorcycle Mechanic Red Seal Glossary

This is the glossary included in the 2012 Red Seal National Occupational Analysis (NOA), essential information for anyone preparing for the Red Seal certification exam.

accessory: an item added to a complete motorcycle, to enhance the visual or riding enjoyment of the motorcycle such as an audio system or a carrying rack.

ancillary: an item fitted to the motorcycle at manufacture to enable or improve the function of the motorcycle.

brake shoe: a cast aluminum, half-circular shoe that holds a bonded brake lining material. When brake is applied, shoe forces lining into brake drum.

chain stretch: wear of pins and bushings of a roller or hy-vo chain, causing chain to lengthen.

chain drive: use of a chain and sprocket to connect gearbox output shaft to rear wheel

chamfer: to bevel an edge of an object or to chamfer edges of port openings in a two-stroke cycle cylinder to prevent piston ring breakage.

chassis: the base frame and components connected directly to it, excluding those parts which provide power, but may include wheels and suspension to become a “rolling chassis”.

crankcase: castings that support and contain the crankshaft flywheel assembly, primary drive and gearbox.

cylinder head: casting that seals top of cylinder and provides a mounting place for spark plug. In four-stroke cycle engine, cylinder head also incorporates an intake and exhaust ports. Both two- and four-stroke cycle engines also have combustion chamber built into cylinderhead.

damper: device which uses oil metered through orifices to control abrupt suspension movement during extension and compression.

damper rod: tube secured to bottom of each fork slider to hold slider onto fork leg. Damper rod controls movement of front suspension by metering hydraulic fluid through orifices in rod.

decarbonize: to remove carbon build-up on piston, combustion chamber, and other parts.

drive plate: drive plate has friction material bonded to its surface. When clutch is engaged, drive plate transfers power to driven plate.

driven plate: a clutch plate which is indexed onto clutch inner hub by tabs or splines around its inside diameter. Driven plate is usually a plain plate (no friction material) and drives gearbox input shaft through clutch inner hub

dry sump: in this system, oil is gravity fed to supply side of oil pump from a remote oil tank. After oil has been pumped through four-stroke cycle engine, it is returned to oil tank by return side of oil pump.

final drive: chains and sprockets or shafts and gears used to connect the gearbox output shaft to rear wheel.

gearbox: a series of shafts and gears which varies ratio of engine to rear wheel speed. Motorcycle gearboxes use from two to seven speeds or ratios.

hydraulic brake: a braking system using hydraulic fluid, piston, and cylinders to provide extremely high pressure for brake application.

hy-vo chain: also known as the silent chain, is a very strong chain made up of toothed plates positioned side by side and held together by pins. Advantage of this type of chain is great strength and quiet operation.

lateral run-out: side-to-side movement (wobble) of a wheel rim.

master cylinder: components in a braking system that produces hydraulic pressure for system.

mechanical brake: a braking system which uses a mechanical advantage by way of levers and cables or rods to apply brakes. A braking system not using hydraulic fluids or hydraulics.

metal sinter: describes the complex compounds used in brake and clutch friction materials.

O-ring: a ring made of neoprene that is used to provide a positive seal. It usually fits into a groove slightly shallower than O-ring, and mated against a flat surface to provide a seal for oil, fuel, or air.

primary drive: use of chain, gear, or belt drive (belts and pulleys) to connect crankshaft to clutch and gearbox into shaft.

push rod: in four-stroke cycle engine, push rods provide means of transferring tappet movement to rocker arm, which opens valves.

recondition: to rebuild a component or return to within factory specifications

shift drum: a drum shaped gearbox component with slots around its outside diameter. It engages with shift mechanism and shift forks. As drum is rotated, drum slots cause shift forks to move sliding gears or dogs causing engagement and disengagement of various gearbox ratios.

shifting fork: a flat forked gearbox component which engages with a slot in a sliding gear or dog. Shifting forks slide back and forth on lateral shafts. Rotation of shift drum or cam plate causes shift fork to move its sliding gear or dog to engage with another gear, locking both gears to shaft.

spoked wheel: a wheel consisting of a rim, spokes, nipples and hub. Spokes are laced between hub and rim and are attached to rim by nipples. Thirty-six or forty spokes are normally used.

sprocket/pulley: a sprocket consists of a wheel with teeth to engage a chain or toothed belt and provide a positive (non-slip) drive. In the case of a belt final drive, often the toothed sprockets are referred to as “pulleys”.

stamped frame: a frame stamped from pieces of sheet metal which are welded together to provide support for engine and suspension.

stamped wheel: a wheel assembly using stamped sheet metal spokes in place of small wire type spokes. A stamped wheel resembles a cast alloy wheel in appearance.

steering damper: a device which uses friction or a hydraulic damper to reduce steering oscillation.

steering head: forward part of frame providing a mounting place for bearings which locate and support steering spindle and fork assembly.

suspension: components which absorb road surface irregularities to smooth motorcycle ride. It is designed to permit controlled wheel movement over irregular surfaces. Basic parts include forks, swing arm and shock absorbers.

swing arm: main member of rear suspension that provides a mounting place for rear wheel and one end of shock absorbers.

torque converter: a fluid turbine which takes place of clutch in primary drive. Oil is used to transmit power through torque converter depending upon engine rpm triple clamps a pair of sturdy brackets that provide a mounting place for fork legs and steering spindle. Triple clamps attach forks to frame through spindle, steering head and steering head bearings.

valve train: all components which directly influence valve operation (cam, cam chain, cam followers, valves, valve springs, valve collars, and keepers in SOHC engine).

variable exhaust valve: the exhaust control valve operates by opening and closing thereby varying the exhaust pressure or back pressure to help scavenge gases more effectively as related to RPM.

Motorcycle Mechanic Red Seal Acronyms

ABS antilock braking system

AGM absorbed glass mat

AIS air injection system

CDI capacitor discharge ignition

ECU electronic control unit

GPS global positioning system

MSDS material safety data sheet

PDI pre-delivery inspection

PPE personal protective equipment

OH&S Occupational Health and Safety

TCI transistor controlled ignition

TPS throttle position sensors

WHMIS Workplace Hazardous Material Information System