Patent ID: 8118000

Claim:
A method of operating an internal combustion engine including at least one combustion chamber having a piston disposed therein, the method comprising: operating the combustion chamber in a four stroke cycle by repeatedly opening a first exhaust valve of the combustion chamber once every four piston strokes via a first cam actuator while holding closed a second exhaust valve of the combustion chamber; operating the combustion chamber in a two stroke cycle by repeatedly opening the first exhaust valve once every four piston strokes via the first cam actuator and repeatedly opening the second exhaust valve once every four piston strokes via a second cam actuator during a different exhaust stroke 360 crank-degrees from the first exhaust valve; and varying operation of the combustion chamber between the four stroke cycle and the two stroke cycle as an operating condition changes by adjusting a lift state between the second cam actuator and the second exhaust valve, and by advancing the first exhaust valve's timing.