US Patent 7849826 Valve system

A valve system includes a first valve provided on an intake or exhaust port; a second valve provided on another intake or exhaust port; a first cam unit on a camshaft, defining first and second lobe heights; and a second cam unit on the camshaft, defining a third lobe height. The first cam unit moves the first valve by a distance of either the first or the second lobe height, and the second cam unit moves the second valve by a distance of the third lobe height.