Power unit for vehicle

A vehicle power unit comprising:

• a speed reducing gear train including a starter driven gear relatively rotatably borne on a crankshaft rotatably borne on a crankcase constituting part of an engine body,
• a starting one-way clutch interposed between the starter driven gear and the crankshaft so as to permit power transmission from the starter driven gear to the side of the crankshaft, the speed reducing gear train and the starting one-way clutch being provided between a starter motor mounted to the engine body and the crankshaft;
• a transmission accommodated in the crankcase, the transmission having gear trains for a plurality of gear speeds which can be selectively established, the gear trains being provided between a main shaft and a counter shaft which have axes parallel to the crankshaft;
• said starter motor being selectively changed over between a normal rotational operation at the time of imparting a starting torque to the crankshaft through the speed reducing gear train and the starting one-way clutch and a reverse rotational operation at the time when power transmission from the starter driven gear to the side of the crankshaft is cut off by the starting one-way clutch;
• and
• a power transmission idle gear meshing with the starter driven gear and the power transmitting gear relatively rotatably borne on the main shaft through a running one-way clutch for permitting power transmission to the side of the main shaft is interposed between the starter driven gear and the power transmitting gear.