MECHANICAL COMPRESSION AND VACUUM RELEASE MECHANISM

Mechanical compression and vacuum release mechanisms which are of simple construction and which significantly reduce the effort required to start an internal combustion engine. In several embodiments, the compression and vacuum release mechanisms include a centrifugally responsive flyweight pivotally mounted to the camshaft, the flyweight coupled to a pair of compression and vacuum release pins which include respective compression and vacuum release cams that are in lifting engagement with the valve actuation structure of one of the intake or exhaust valves of the engine during engine starting to relieve compression and vacuum within the combustion chamber and thereby facilitate easier engine starting. After the engine is started and reaches running speed, the flyweight pivots responsive to centrifugal force and in turn pivots the compression and vacuum release cams out of engagement with the valve actuation structure of the intake or exhaust valve to allow the engine to operate normally.