Dry Sump Lubrication

An engine lubrication system commonly used on motorcycles and ATVs. This system is set up so that the bulk of the engine oil is stored in a remote location such as an oil tank or the motorcycle frame itself. The oil is fed into the supply side of the oil pump by gravity and is pumped through the engine and then returned to the oil tank or frame by the return side of the oil pump. Dry sump lubrication systems allow the engine to be placed lower in the frame for a lower center of gravity to improve handling.

Dry Clutch

A clutch fitted on a motorcycle engine that is not located in an oil bath. Used primarily in high performance or racing motorcycles, a dry clutch doesn’t consume as much power as a wet clutch, but it is nosier and tends to wear out sooner.

Wet Clutch

A multi-plate motorcycle clutch fitted inside the engine which runs in an oil bath.

Water Pump

A pump that circulates coolant through a water-cooled motorcycle engine. Typically uses an impeller to force the coolant through the body of the water pump.

Steering Damper

A device which uses mechanical or hydraulic friction to reduce motorcycle steering oscillation at high speeds.

Single-leading Shoe Drum Brakes

A drum brake system having two brake shoes; one shoe is leading and one is trailing. The leading shoe wedges itself into the drum, providing more braking action than the trailing shoe.

Single Cradle Frame

A motorcycle frame that has one down tube from the steering neck to the front of the engine.

Shift Drum

A shift drum is a cylindrical shaped transmission component with machined slots around its outside diameter. When actuated by the external shift mechanism it moves the the internal shift forks. As the shift drum is rotated, drum slots cause the shift forks to move sliding gears or dogs, causing the engagement and disengagement of various transmission ratios.

Shaft Drive

Many touring motorcycles, cruiser style motorcycles and ATVs utilize a shaft drive as their final drive. A shaft drive system consists of a drive shaft, universal joints and gears to connect the transmission output shaft to the rear wheel. Shaft drive is a very low maintenance type of final drive, but it’s heavy and cannot be easily regeared to a different final drive gear ratio.

Pilot Air Screw

A screw mounted on the side or bottom of a motorcycle carburetor that allows adjustment of the air/fuel ratio in the pilot circuit of a slide type carburetor. Also known as the idle air screw or the low speed air screw.

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