The timing of the ignition spark on the power stroke of the combustion cycle.  The timing can be controlled by electronic or mechanical means.  Modern ignition systems can advance or retard the timing based on RPM, speed, throttle position, gear position and even wheel spin.

For mecanical engine timing see the Cam Chain topic.

Anyone who has ridden a motorcycle fast before can attest to having to deal with unwanted head shake at one time or another. It is when this head shake gets out of control that we call it a tank slapper.

Keith Code, author of the book, A Twist of the Wrist II explains it as ‘The process of head shake begins when the tire hits a ripple and along with the suspension, compresses. This throws the wheel slightly off-center. When the suspension and tire release, the wheel is light and flicks back toward a centered position, but again, slightly off-center. Still off-center when it loads again from the next ripple, again it is flicked past its centered position. The cycle of flicking back and forth repeats as the front-end seeks to stabilize through this automatic and necessary self-correcting process. Any bike will do it, and what most riders fail to realize is that this shake is a necessary part of the bike s suspension system.”

A tire that retains air without an inner tube. An inner tube (used on a tube-type tire) is necessary to retain air pressure when the wheel design (especially wire spoke wheels) or the tire cannot do so. However, an inner tube typically deflates rapidly when punctured, and this sudden deflation can cause a quick loss of control on a motorcycle. A tubeless tire typically deflates much more slowly, providing a motorcyclist with warning before control is reduced significantly. Whether a tube-type or tubeless tire is chosen normally depends on the kind of wheel to which it is fitted and the manufacturers recommendations.

An instrument used to determine engine speed in revolutions per minute (rpm). Most motorcycles have a tachometer that sits next to the speedometer in the instrument cluster.

The rear facing brake shoe on a drum brake system.

Can refer to the process of adjusting a crankshaft so that it spins within specification. More often the term is used to refer to the painstaking process of adjusting a spoked wheel to correct any irregularities in lateral and radial runout, also known as wobble and hop. This is done by tightening and/or loosening spoke nipples until the runout readings are within specification.

Upon both disassembly and re-assembly of various motorcycle components, most notably motorcycle engines, there is predetermined numerical or pattern sequence in which bolts should be removed or tightened. Failure to follow this sequence can result in component damage, specifically, warping or cracking the component. In the case of a cylinder head, the manufacturer often recommends following a criss-cross pattern in addition to a series of tightening stages. As a general rule of thumb, tighten larger diameter fasteners first and then the smaller ones.

The distance (in inches or millimeters) between an imaginary line drawn down the center of the front forks of a motorcycle to the ground  and a vertical line drawn through the front axle center to the ground.

The top end of an engine typically refers to all of the components from the cylinder base gasket up, including  the cylinder, cylinder head and piston but excluding the connecting rod. Two-stroke engines are famous for requiring top-end jobs on a frequent basis because they produce power every revolution of the crankshaft, while four stroke engines only produce power every two crankshaft revolutions.

When a piston travels the length of its stroke in normal operation, it is said to have reached top dead center when it is at the upper most position in the cylinder, farthest away from the crankshaft.