the disks are solid full of material rid of passages the disks comprise exhaust valve ports 9 and intake valve ports 10 the cylinder head 5 comprises a cavity 11 having at opposite sides a pair of chamber ports 12 each having a flat lip 13 each flat lip 13 being in sealing cooperation with the respective flat front 8 of the disk rotary valve 1 the external flat surfaces 14 of the discs cooperate with respective flat surfaces 15 on the cylinder head 5 through passages 16 made in each disk the exhaust valve port 9 communicates with a respective passageway exhaust port 17 on the cylinder head 5 through proper recesses 18 made on each disk the intake valve port 10 communicates with the space 19 around the periphery of the disk which in turn communicates with a respective passageway intake port 20 on the cylinder head in this design any gas leakage through the chamber ports 12 out of the combustion chamber 50 ends into the space 19 around the peripheries of the disks with the spaces 19 being sealed from the exhaust the gas leakage re enters is recycled into the combustion chamber during the next suction cycle this way even.