The rocker arm is a pivotal component in a motorcycle’s engine valvetrain that transfers the motion from the camshaft to the engine's valves. It is typically a lever-like mechanism that pivots on a shaft or bearing, pushing the valve open and then allowing it to close as the camshaft rotates. By converting the rotational motion of the camshaft into the linear motion needed to operate the valves, the rocker arm plays a critical role in regulating the engine’s air-fuel intake and exhaust.