The complete cycle of an engine requires four piston strokes: intake, compression power, and exhaust.
发动机完整的循环要求有活塞的四个冲程：进气、压缩、做功、排气。
2
The cycle of operation of the four-stoke engine begins with the piston at TDC and the intake valve open.
四冲程发动机的工作循环是以活塞在上止点、进气门打开为开始的。
3
Otto built the practical four-stroke internal combustion engine called the "Otto Cycle Engine, " and as soon as he had completed his engine, he built it into a motorcycle.