Two-wheeled motor vehicle and power unit

摘要

A motorcycle includes: an internal combustion engine having a crankshaft; a transmission mechanism; a centrifugal start-up clutch; and a torque converter. The centrifugal start-up clutch and the torque converter are provided between the crankshaft and the transmission mechanism. The motorcycle further includes a one-way clutch provided between the crankshaft and the torque converter so that the one-way clutch transmits power from the transmission mechanism to the crankshaft only when a driving force transmitted from a wheel toward the transmission mechanism is larger than a driving force of the internal combustion engine and a rotational speed of the crank shaft is not lower than a predetermined value.