| 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 that is required for the motorcycle to be compliant to safe road operation |
| brake pad |
a stamped section of steel with friction material bonded to it, which is pressed against the brake disc when the brake is applied |
| 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 drive |
use of a chain and sprockets to connect gearbox output shaft to rear wheel |
| chamfer |
to bevel an edge of an object; e.g. chamfer edges of port openings in a two-stroke 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, and may also include primary drive and gearbox |
| cylinder head |
casting that seals top of cylinder and provides a mounting place for spark plug. In four-stroke engine, cylinder head also incorporates intake and exhaust ports. Both two- and four-stroke engines also have combustion chamber built into cylinder head |
| 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 suspension by metering hydraulic fluid through orifices in rod |
| damping |
controlling oil metered through orifices to control abrupt suspension movement during extension and compression |
| decarbonize |
to remove carbon build-up on piston, combustion chamber, and other parts |
| diagnostic software |
automatic computer program sequence that determines the operational status within the software, hardware or any combination thereof in a component, a system, or a network of systems |
| 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 engine, it is returned to oil tank by return oil pump |
| final drive |
chains, sprockets, belts, pulleys, shafts and gears used to connect the gearbox output shaft to rear wheel |
| friction plate |
a plate that has friction material bonded to its surface. When clutch is engaged, friction plate transfers power to steel plate |
| friction shoe |
a cast aluminum, half-circular shoe that holds a bonded friction lining material; it is used to transfer power in a centrifugal clutch |
| gearbox |
a series of shafts and gears which varies ratio of engine to rear wheel speed. Motorcycle gearboxes use two or more speeds or ratios |
| hydraulic brake |
a braking system using hydraulic fluid, piston, and cylinders to provide extremely high pressure for brake application |
| induction air leak test |
commonly referred to as a “vacuum leak test”. An air induction leak test is used to identify unmetered air entering the intake downstream of the throttle plate |
| lateral run-out |
side-to-side movement (wobble) of a wheel rim; also known as axial run-out |
| manometer |
an instrument used to measure positive or negative pressures |
| master cylinder |
components in hydraulic systems that produce hydraulic pressure for systems |
| 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 |
| O-ring |
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, coolant or air |
| primary drive |
use of chain, gear, or belt drive (belts and pulleys) to connect crankshaft to clutch and gearbox into shaft |
| 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 |
| shift fork |
a flat forked gearbox component which engages with a slot in a sliding gear or dog. Shift forks slide back and forth on lateral shafts. Rotation of shift drum causes shift fork to move its sliding gear or dog to engage with another gear, locking both gears to shaft |
| sintered |
the complex compounds used in brake and clutch friction materials |
| spoked wheel |
a wheel consisting of a rim, spokes, nipples and hub. Spokes are laced between hub and rim and are attached to rim. |
| 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 |
| steel plate |
a steel plate is indexed onto clutch inner hub by tabs or splines around its inside diameter. Steel plate is usually a plain plate (no friction material) and drives gearbox input shaft through clutch inner hub |
| steering damper |
a device which reduces 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 |
| 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 four-stroke engines. |
| variable exhaust valve |
the exhaust control valve operates by opening and closing thereby varying the exhaust pressure |