| 摘要 |
PROBLEM TO BE SOLVED: To lower the center of gravity of an engine and shorten the whole height of the engine, without enlarging a crankcase and increasing weight, in a motorcycle engine including the crankcase composed of a pair of case halves supporting a crankshaft through a bearing and also connected to each other through a mating surface along a plane perpendicular to the axis of a crankshaft, and an engine hanger boss provided to the crankcase and fixed on a frame by an engine hanger. SOLUTION: The crankcase is provided with an annular support wall extending in the crankshaft direction and surrounding the periphery of the bearing and the engine hanger boss arranged below the annular support wall. A pair of reinforcing ribs extending toward the engine hanger boss is provided along the tangent direction of the periphery of the annular support wall from the annular support wall. COPYRIGHT: (C)2010,JPO&INPIT
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