what you are saying about 1/2 revolutions is wrong.
if you changed your word "revolution" to "cycle" it would be better.
If you think about it, any (piston) angine of any size, shape, configuration or number of cylinders will revolve twice to make one complete cycle.
lets break it down into strokes (half rotations) 2wo strokes per revolution, two recolutions per cycle. this equals 4 strokes per cycle (hence 4 stroke engine)