Abstract: An internal combustion engine with an exhaust valve formed in the upper surface of the piston and driven by a valve stem connected to the engine crankshaft by an operating arm mounted parallel to the connecting rod and axially movable with respect thereto by means of a cam follower and rolling engagement with a cam on the connecting rod journal of the crankshaft. At least one exhaust tube is mounted in the cylinder and secured to the piston and more specifically to an exhaust chamber formed in the piston below the exhaust valve. The exhaust tube is a telescoping tube which extends from the piston to a wall of the engine block.