Abstract: A combustion engine compression release mechanism having a cam shaft with a cam operating an exhaust valve lifter and a cam shank operating the same exhaust valve lifter independently of the cam during the starting speed of the engine in order to release the compression within the engine cylinder. The cam shank is mounted on the cam shaft for rotatable motion and has a cam portion to engage the exhaust valve lifter during the low starting speed of the engine. A rocker arm is attached to the cam shank to extend radially from the cam shank and is provided by a guide. A slide block is mounted in the guide for motion along the guide and is fixed to an eccentric body adapted to move by effect of centrifugal force with relation to the cam shaft and to operate the slide block. The eccentric body is urged by a spring into a position where the cam portion of the cam shank engages the exhaust valve lifter.