Piston Inlet Port

From CycleChaos

A Piston Inlet Port engine is the simplest of all two-stroke designs. All functions are controlled solely by the piston covering and uncovering the ports as it moves up and down in the cylinder. A fundamental difference from typical four stroke engines is that the crankcase is sealed and forms part of the induction process.

Also see: Rotary Disc Valve and Reed Inlet Valve