Abstract: A centrifugally responsive compression release mechanism for an internal combustion engine. The release mechanism includes a yoke pivotally mounted to the camshaft and having an auxiliary cam member that is movable between an operative valve-unseating position and an inoperative position. A counterweight is associated with the legs of the yoke and causes the center of mass of the yoke to be offset from the plane containing the pivot axis. With this configuration, the yoke is biased by gravity at low rotational speeds to position the cam member in the operative valve-unseating position to thereby release compression in the combustion chamber of the engine. At engine running speeds, centrifugal force overcomes the gravitational force to pivot the yoke and the attached cam member to the inoperative position so that normal operation of the engine is not impaired.