The fuel cap is an important part of any vehicle. This prevents gasoline from spilling out of the vehicle and can also prevent outside debris from entering your fuel tank. On motorcycles it is common for the fuel cap to have a lock on it to prevent someone from stealing your gas.
A fuel pump is used to supply fuel from the tank to the engine. Earlier vehicles with carburetors used a mechanical low pressure pump. Modern engines have fuel injection instead of carburetor and uses electric high pressure pumps.
The pads that press against the brake disk to stop the vehicle by using friction are called friction pads. They are also called brake pads. Drum brakes have brake shoes that fulfil a similar purpose.
A four stroke engine is a type of internal combustion engine that uses four strokes of the piston to complete one cycle of intake, compression, combustion and exhaustion. The crankshaft completes two rotations for every single cycle. Most cars and bikes today use four stroke engines.