A power unit includes an engine and a transmission mechanism, which is integrated with the engine, for transfer of power from the engine. The engine includes a crankshaft which converts a reciprocal motion of a piston to produce a rotary motion, a crankcase supporting the crankshaft, a cylinder extending from the crankcase so as to protrude in a reciprocating direction of the piston, and a cylinder head coupled to a protruding end of the cylinder. The transmission mechanism includes an output shaft arranged at one side of the crankshaft in an axial direction of the crankshaft to provide, as an output, rotational power from the crankshaft. The output shaft is positioned to a side of the crankshaft that faces the cylinder head with respect to the reciprocating direction and is positioned so as to overlap with the cylinder or the cylinder head when viewed in the axial direction.

An engine includes: ignition plugs which ignite an air-fuel mixture in combustion chambers; a power transmission member which transfers rotary motion of a crankshaft to a valve operation control mechanism for air intake and exhaust valves; and a transmission member housing space having the power transmission member disposed therein. The ignition plugs include first and second ignition plugs for each of the combustion chambers. The first ignition plug is located on a cylinder axis, and the second plug is arranged offset relative to the first ignition plug so as to be away from the transmission member housing space in a widthwise direction of the engine along which the crankshaft extends.

A power device includes: a plurality of shafts; and a case that rotatably supports the plurality of shafts. At least one of the plurality of shafts has a protruding end portion protruding outward from the case at least at one end portion in an axial direction. An output unit capable of rotationally driving a driven device is at the protruding end portion.

An engine includes a crank shaft inside a crankcase and an oil pan and penetrates the crankcase and the oil pan in an up-down direction. An oil pump and an oil strainer are provided inside the oil pan. The oil pump is coaxial with the crank shaft and is driven by the crank shaft. The crank shaft includes a first region and a second region respectively supported pivotably by a plate-shaped support and the crankcase. The support is provided in the crankcase such that both surfaces of the support are covered by the crankcase and the oil pan and allows communication between the crankcase and the oil pan.

An engine includes a crank shaft inside a crankcase and an oil pan and penetrates the crankcase and the oil pan in an up-down direction. An oil pump and an oil strainer are provided inside the oil pan. The oil pump is coaxial with the crank shaft and is driven by the crank shaft. The crank shaft includes a first region and a second region respectively supported pivotably by a plate-shaped support and the crankcase. The support is provided in the crankcase such that both surfaces of the support are covered by the crankcase and the oil pan and allows communication between the crankcase and the oil pan.

A structural oil pan for a vehicle is formed from polymeric material, The structural oil pan includes a bracket portion configured for mounting to the vehicle, and a pan portion integrated with the bracket portion and defining an oil reservoir. The structural oil pan also includes a structural section defining a cavity within at least one of the bracket portion and the pan portion for reducing vibration.

Systems and methods for use in controlling a hydraulically powered AC generator are provided. One control system includes a valve system. The valve system includes a fixed valve configured to provide a substantially constant flow rate of the fluid through the fixed valve to the hydraulically powered AC generator. The valve system further includes a variable valve configured to provide a variable flow rate of the fluid through the variable valve to the hydraulically powered AC generator. The control system further includes a sensor device configured to measure a speed of movement of a component of the hydraulically powered AC generator. The control system further includes a control circuit configured to control the variable flow rate of the variable valve based on the speed of movement of the component measured by the sensor device.

Systems and methods for use in controlling a hydraulically powered AC generator are provided. One control system includes a valve system. The valve system includes a fixed valve configured to provide a substantially constant flow rate of the fluid through the fixed valve to the hydraulically powered AC generator. The valve system further includes a variable valve configured to provide a variable flow rate of the fluid through the variable valve to the hydraulically powered AC generator. The control system further includes a sensor device configured to measure a speed of movement of a component of the hydraulically powered AC generator. The control system further includes a control circuit configured to control the variable flow rate of the variable valve based on the speed of movement of the component measured by the sensor device.

An exhaust device for a saddle-type vehicle having a pipe section with respect to a vehicle body and housing a catalyzer therein, and a muffler connected to a rear end of the pipe section includes an upstream oxygen sensor positioned upstream of the catalyzer and a downstream oxygen sensor positioned downstream of the catalyzer. The downstream oxygen sensor is disposed in either a position overlapping a main stand for supporting a motorcycle as viewed from below the vehicle body when the main stand is stored, or a position overlapping a stand receiver for abutting against the main stand as viewed from below the vehicle body when the main stand is stored. The pipe section includes a larger-diameter portion having an increased diameter for housing the catalyzer therein.

An exhaust device for a saddle-type vehicle having a pipe section with respect to a vehicle body and housing a catalyzer therein, and a muffler connected to a rear end of the pipe section includes an upstream oxygen sensor disposed on the pipe section and positioned upstream of the catalyzer and a downstream oxygen sensor disposed on the pipe section and positioned downstream of the catalyzer. The pipe section includes a larger-diameter portion having an increased diameter for housing the catalyzer therein. The downstream oxygen sensor is disposed in the larger-diameter portion. The upstream oxygen sensor and the downstream oxygen sensor are positioned upwardly of a central line of the larger-diameter portion with respect to the vehicle body as viewed in side elevation of the vehicle body.