The crankshaft is the main rotating mechanism of the engine. It is responsible for the change of the upper and lower reciprocating motion of the piston to its own circular motion, and usually we say the engine speed is the speed of the crankshaft.

Crankshaft will be due to the oil is not clean and the force of the shaft neck caused by the big end of the connecting rod and the shaft neck wear, if there is a large particles of hard impurities in the oil, there is also the risk of scratches on the neck surface. If the wear is serious, it is likely to affect the piston up and down motion of the length of the stroke, reduce the combustion efficiency, the natural will be smaller power output. In addition, the crankshaft may also be due to insufficient lubrication or oil is too thin, resulting in burns on the surface of the shaft, in severe cases will affect the reciprocating motion of the piston. So be sure to use the appropriate viscosity of the lubricating oil, and to ensure the cleanliness of the oil.