To provide a valve for a four-stroke engine, that has an intake and an exhaust valve hole bisecting one cylindrical valve element rotated directly above a piston, for noncontacting, smooth, silent and durable operation.

A hole bisects a valve element, in such a way as to extend from an intake port in the left of a cylinder head and to lead intake gas from a right obliquely upward through a carburetor. Another bisecting hole extends from an exhaust port in the right to lead exhaust gas left obliquely upward to an exhaust manifold through the left side connecting to a muffler.