With a piston starting its power stroke every 180 degrees of crankshaft rotation, and the crank throws 180 degrees apart, all the pistons finish their power stroke before the next piston starts its power stroke. This results in gaps between power strokes and a pulsating delivery of torque to the flywheel, causing a rotational vibration on the entire engine along the crankshaft axis. By contrast, in engines with more cylinders the power strokes overlap; the next piston starts its power stroke before the previous one has finished, and the delivery of power is much smoother.