摘要 |
In a power unit, a counter shaft of a transmission and a crank shaft of an internal combustion engine, both located below a main shaft of the transmission, are arranged parallel to each other on a separating plane H of a crankcase. In a transmission mechanism T which drives an oil pump located below the separating plane H, a drive sprocket is placed on the main shaft of the transmission and a driven sprocket is placed on a drive shaft of the oil pump. An endless chain slidably touches a slender long chain guide along the running direction of the endless chain. The chain guide is fitted only to an end wall of an upper crankcase at its fitting part. The chain guide stretches across the end wall of the upper crankcase and an end wall of a lower crankcase, and effectively suppresses vibration of the endless chain.
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