Motorcycle engines can be classified into single-cylinder engines and multi-cylinder engines according to the number of cylinders. Multi-cylinder engines are further divided into two-cylinder, three-cylinder, four-cylinder, five-cylinder, six-cylinder engines, etc.

A single-cylinder engine is called a single-cylinder engine. Since the crankshaft of a single-cylinder engine is short and light, the gyroscopic effect is small, and it is light, flexible and easy to control when turning. Generally speaking, small-displacement motorcycles below 125 ml basically use single-cylinder engines, and off-road motorcycles with harsh working environments also mostly use single-cylinder engines.

The engine above the two cylinders is called a multi-cylinder engine. Multi-cylinder engines have many advantages, such as smooth operation, allowing the engine speed to be increased, which is conducive to obtaining more power. However, multi-cylinder engines have many disadvantages, such as large size, large mass, and complex structure, so the manufacturing and maintenance costs are high. For in-line multi-cylinder engines, due to the long crankshaft and large mass, the gyroscopic effect of the engine is obvious, and the driver will find it difficult when the vehicle turns.