Maintenance Free Battery
A sealed battery that requires no additional water or electrolyte during its lifespan. Also known as an MF battery.
Fuse
Most motorcycles have a fuse block which houses a variety of fuses for different electrical circuits on the vehicle. Fuses protect electrical circuits from overloading by sacrificing themselves before damage can occur to electrical components or wires connected to the circuit. Most fuses contain a small filament, much like an incandescent light-bulb. When a circuit is overloaded the filament or link in the fuse melts and opens the circuit to prevent further damage. Fuses are rated by amperage limits they are designed to withstand. If the wrong size fuse is used it can cause damage to a circuit or cause premature failure of the fuse. Never replace a fuse with metal foil or wire once it has blown. AC circuits (ignition or lighting) will not be fused.
Dial Bore Gauge
A precision measurement tool utilizing a telescoping gauge and dial indicator to give readings of inside diameter measurements. Often used for inspection of cylinder bores for taper and out of round.
Cylinder Bore
Refers to the diameter of the cylinder that the piston fits into in a motorcycle engine.
Cylinder
A precisely machined hole in the cylinder block of a motorcycle engine. The cylinder guides the piston as it travels up and down inside it.
Anaerobic Sealant
A chemical sealant or adhesive that cures in the absence of air (anaerobic means without air). Typically used for retaining and locking threaded components together, such as nuts and bolts. Available in different bonding strengths suited for particular applications. Most service manuals will note which type of bonding agent is required for reassembly of a component.
You can purchase anaerobic sealants at your local motorcycle shop or automotive store. The most popular brand of anaerobic sealant used in motorcycle applications is Loctite. The Company produces a variety of special sealants of which three are the most common:
- Loctite Blue is a nonpermanent removable type that is used on non-critical fasteners that you may have to remove again soon. It works well for holding bodywork fasteners in place.
- Loctite Red is a high-strength sealant that is used on critical components that are rarely serviced such as a clutch hub nut. Depending on the application you may need a propane torch or heat gun to heat the sealant so it will release.
- Loctite Green is a permanent adhesive used on applications where you do not want the assembly to come free. While it is often not needed and should be used with care, Green works well on cylinder studs, exhaust studs and for thread repair work.
Air Filter
An air cleaner or air filter is a device for filtering, cleaning, and removing debris from the air being sucked into the engine. A dirty air cleaner will cause a motorcycle engine to exhibit decreased performance - the engine will run rich, burning more fuel than necessary - it may even foul the spark plug(s). Air filter designs have changed over the years but are the same in principle - they are typically manufactured from paper, oiled foam, oiled gauze, or wire mesh. Paper and oiled gauze air filters are usually pleated to increase the surface area for better breathing and longer service intervals.
After Bottom Dead Center (ABDC)
When a piston travels the length of its stroke, in normal operation, it is said to have reached bottom dead center when it is at the lowest position in the cylinder, closest to the crankshaft. The point at which the piston is starting to travel back up on its stroke is called after bottom dead center.
