The cylinder head (5) is fixed to the block (13). It has a domed combustion chamber with an ignition plug and two channels (1,2) leading to two cylindrical shafts (3). One shaft is supplied with fuel air mixture from the carburettor and the other feeds the exhaust system. Each shaft is connected with the crankshaft (6) so that it rotates in time with the piston (14) motion. As the orifices (14) in the shafts line up with the channels mixture can be drawn in or exhaust expelled. Sealing is completed when the orifices and channels are not aligned.
