A power cycle in a pushrod four-stroke motorcycle engine requires 4 strokes of the piston. On the intake stroke the intake valve opens and fuel mixture flows into the cylinder. When the piston starts to move to the top or upwards both valves are closed and compression occurs with fuel and air. As the result of the firing the force created pushes the piston down and creates the power stroke. During the downward travel the exhaust valve opens the remains of the exhaust from previous charge is pushed out. Now again when the piston is at it's top position the intake valve opens, the exhaust flow starts the intake flow and the exhaust valve closes.