The crankshaft is located inside the engine block and is connected to the pistons by connecting rods. It works by converting the reciprocating linear motion of the pistons into the rotary motion necessary to propel the motorcycle. The lifespan of a crankshaft depends on proper maintenance and operating conditions. In general, a well-maintained crankshaft can last for many miles, and even the entire lifespan of the engine if kept in good condition. The crankshaft is the hidden heart of the engine, driving your motorcycle's speed.