Cc is a unit of volume, which can be used as a unit of measurement for solids, liquids and gases. 50cc is a motorcycle with small displacement and less than 50ml (including 50ml), which is called moped. Motorcycles with more than 50ml are called large displacement motorcycles. Any locomotive with a displacement of more than 50cc, or a horsepower of more than 40 horses and a maximum speed of more than 45 kilometers per hour can be called a heavy locomotive. Motorcycle engines with large displacement will have greater output, stronger cars and faster speed. The main factor that determines the size of a motorcycle is the engine, and the size of the engine is closely related to the displacement. Therefore, the larger the displacement of a motorcycle, the larger the engine, and the larger the frame and wheelbase of the engine.