Rotary valve internal combustion engine

A rotary valve internal combustion engine having a piston connected to a crankshaft and reciprocatable in a cylinder, a combustion chamber being defined in part by the piston, and a rotary valve rotatable in a valve housing fixed relative to the cylinder, the rotary valve having a valve body containing a volume defining, in part, the combustion chamber and further having in a wall part thereof a port giving, during rotation of the valve, fluid communication successively to and from the combustion chamber via inlet and exhaust ports in the valve housing, wherein the valve is mounted in a bearing arrangement which restrains the valve from movement in the axial direction but permits movement in the radial direction, wherein the bearing arrangement comprises a single race ball bearing, wherein the valve body is coaxial with a drive shaft of smaller diameter, the drive shaft extending through the inner race of the bearing with a clearance therebetween to enable the valve to move in the radial direction, the shoulder formed between the valve body and the shaft abutting the inner race to restrain axial movement of the valve when subjected to positive combustion pressure, wherein the shaft has a flange overlapping the side face of the inner bearing race away from the valve body, the flange restraining movement of the valve towards the cylinder, there being a clearance between the flange and the said inner race such that the valve is not clamped between the inner race but is able to float radially within the inner race.