Why does the newly bought motorcycle engine have abnormal noise?

The reason why the newly bought motorcycle engine piston knocks on the cylinder is usually that the fit clearance between the piston and the cylinder is too large, and when the engine really works.

Under the pressure of high-pressure gas, the piston swings in the cylinder, knocking on the cylinder wall and producing sound. In addition, the piston is anti-elliptical, the connecting rod is bent or twisted, and the piston pin and the connecting rod copper sleeve (bearing) are too tight, which will also cause the piston to knock on the cylinder.

Main advantages:

In motorcycle engine, the piston is a part that transfers the explosive power of fuel to the outside. The first thing is the strong impact of high temperature and high pressure in the combustion chamber. According to relevant data, at the moment of ignition and explosion of the engine combustion chamber, the gas temperature is as high as 2000℃-2500℃ and the pressure is about 4.90MPa(50kg/ cm2), and the piston head will be impacted by the explosion force of 5000-23000 N and the higher gas temperature.