In the two-cycle engine, the piston ACTS as a valve, clearing valve ports in the cylinder wall as it nears BDC.

在二行程发动机中，活塞起到阀门的作用，当活塞接近下止点时，使气缸壁上的进排气口打开。

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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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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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