Patent ID: 7500460

Claim:
In an internal combustion engine of the type including a crankcase for accommodating a crank mechanism and a transmission case for accommodating a transmission mechanism, where the crankcase and the transmission case are integrated in a power unit case, the improvement comprising a starter-motor mounting structure for supporting a starter motor on the power unit case, in which the crankcase and the transmission case are arranged in a front-to-rear direction, wherein: the power unit case comprises a cylinder block that projects from the crankcase so as to be tilted forward, the cylinder block having a rear inclined surface with a front mounting boss formed thereon; the power unit case also comprises a transmission case having an upper wall which is raised upwardly to accommodate a main shaft that is positioned higher than a counter shaft of the transmission mechanism, the upper wall having a rear mounting boss formed in a front wall surface of a raised portion of the upper wall of the transmission case; wherein the front mounting boss and the rear mounting boss are offset from each other in an axial crankshaft direction; and a front bracket and a rear bracket that extend from the starter motor are respectively fastened to the front mounting boss and the rear mounting boss.