Abstract: An internal combustion engine assembly includes a crankcase and a cam housing. The crankcase includes a crankcase cavity configured to receive a counterweight. The cam housing includes a cam housing cavity configured to receive a camshaft. A pump is positioned within the cam housing. The pump is configured to draw oil from an oil reservoir defined by the cam housing cavity. A crankshaft supports the counterweight for rotation therewith. The crankshaft is rotatably supported within the cam housing and is coupled to drive the pump. A bearing supports the crankshaft between the crankcase cavity and the cam housing cavity. The bearing includes an outer race. A seal is positioned between the pump and the bearing. The seal is positioned against the outer race to block the transmission of pressure fluctuations between the crankcase cavity and the oil reservoir.

Abstract: Each cylinder of a slanted, in-line, overhead valve, internal combustion engine has intake and exhaust valves with axes which extend radially from and perpendicular to the camshaft axis. The camshaft axis is above an inclined plane which includes the central axes of the cylinders, and the valve axes are mutually divergent to intersect this plane at different angles.

Abstract: A spark-ignition four-stroke gasoline engine, of the commonly mass-produced type having a plurality of cylinders provided each with two poppet valves mounted in a cylinder-head of the engine and constituting respectively an inlet valve, for passing a fuel-air mixture to the cylinder, and an exhaust valve for passing exhaust gases to an exhaust manifold of the engine, is given exhaust valves which are at least 7% greater in area than the inlet valves.