If it needs only two strokes to complete a cycle, it is called a two-stroke cycle engine or, for short, a two-cycle engine.

如果发动机完成一个工作循环，只需要两个行程，就称为两冲程循环发动机，或者简称两冲程发动机。

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A two-stroke engine has no moving valves, and the spark plug fires each time the piston hits the top of its cycle.

二冲程发动机没有移动的阀，火花塞每次点火活塞到达循环顶端。

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The size, weight, and cost of the engine per horsepower are therefore less, and two-stroke-cycle engines are used in motorcycles and smaller machines (e. g. , lawnmowers and power rakes).

因此，每马力所要求的机器尺寸、重量和价格成本也就降低了，所以二冲程循环发动机多用于摩托车和小型机器（如割草机和动力耙）。

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The size, weight, and cost of the engine per horsepower are therefore less, and two-stroke-cycle engines are used in motorcycles and smaller machines (e. g. , lawnmowers and power rakes).

因此，每马力所要求的机器尺寸、重量和价格成本也就降低了，所以二冲程循环发动机多用于摩托车和小型机器（如割草机和动力耙）。

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