What are the symptoms and causes of piston slap in motorcycles?

[LeMia]

The symptoms of piston slap are: When the engine is idling, a crisp knocking sound can be heard in the upper part of the cylinder; the sound is more noticeable when the engine is cold and diminishes or disappears when the engine is warm. The causes of piston slap are: Excessive clearance between the piston and cylinder; the piston is installed backward or deformed, disrupting the normal clearance between the piston and cylinder; poor lubrication of the cylinder wall, preventing the formation of a normal oil film between the piston and cylinder wall, leading to direct contact; bent or twisted connecting rod, causing abnormal wear in the cylinder; severe carbon buildup in the combustion chamber increasing the compression ratio in diesel engines, resulting in excessively high gas pressure and temperature, causing the atomized diesel injected into the cylinder to ignite and combust upon encountering the high-temperature and high-pressure gas, leading to so-called knocking.