Patent ID: 7325527

Claim:
An internal combustion engine comprising: a power unit case having a crankcase, an integrated transmission housing, a first housing flange and a second housing flange; a crankshaft having first and second crankshaft ends, the crankshaft being supported for rotation about a crankshaft axis in the crankcase, the power unit case having a central plane defined as a vertical plane being perpendicular to the crankshaft axis and intersecting the crankshaft generally at a midpoint between the two crankshaft ends; an output shaft supported for rotation about an output shaft axis in the crankcase, the output shaft axis and the crankshaft axis defining a reference plane; a first oil pump comprising: a first oil pump chamber disposed at least partially in the power unit case; an oil pump shaft disposed at least partially in the first oil pump chamber and being supported for rotation about an oil pump shaft axis, a normal projection of the oil pump shaft axis onto the reference plane being located between the crankshaft axis and the output shaft axis; and a first oil pump rotor disposed in the first oil pump chamber on the oil pump shaft so as to rotate therewith about the oil pump shaft axis; a first housing cover mounted to the first housing flange on a first side of the power unit case, the first housing cover being removable, and, when mounted, forming part of the power unit case, the first housing cover being one of a clutch cover and an ignition cover; and an oil pump cover mounted to the second housing flange on the first side of the power unit case to close the first oil pump chamber, the oil pump cover being removable to provide access to the first oil pump chamber, and when mounted, forming part of the power unit case, the oil pump cover being separate from the first housing cover.