How to distinguish whether the engine is a single-cylinder engine or a two-cylinder engine?

A two-stroke cylinder has two sections (cylinder+cylinder head) and a four-stroke cylinder has three sections (cylinder+cylinder head+valve cover). The sound of single-cylinder engine is not obvious. Four strokes have a sense of rhythm Displacement can usually be expressed by model or can be found on the engine nameplate. It is impossible to accurately identify the engine size.