Abstract: A power unit for a motorcycle having a clutch operation assisting device. The clutch operation assisting device includes a push shaft, a bearing plate that supports the push shaft, and a first rotary plate rotatably supported on the bearing plate and connected to a clutch wire. The first rotary plate causes the push shaft to slide as it rotates and is gear-coupled to a second rotary plate. A spring unit that applies an assist force in a direction for disengaging a friction clutch is pin-coupled to the second rotary plate. The spring unit is supported on a mounting seat in a swingable manner and is installed such that, as viewed from the axial direction of the push shaft, the expansion/contraction direction of an auxiliary spring in the spring unit does not pass through a rotation center of the pressure plate.

Abstract: In a stepwise automatic transmission, a mass is concentrated in a longitudinal direction thereof. The stepwise automatic transmission includes an input shaft, an intermediate shaft, an output shaft, a first clutch which is connected and disconnected in accordance with a rotation speed of the input shaft, first and second power transmission mechanisms, and a second clutch which is connected and disconnected in accordance with rotation speed of the intermediate shaft. The intermediate shaft is disposed rearward of the input shaft. When the first clutch is connected, the first power transmission mechanism transmits rotation of the input shaft to the intermediate shaft. The second clutch is provided on the intermediate shaft. When the second clutch is connected, the second power transmission mechanism transmits rotation of the intermediate shaft to the output shaft. A front end of the second clutch is located forward of a rear end of the first clutch as viewed from an axial direction of the input shaft.

Abstract: A motorcycle having high durability and a large space below a seat includes an internal space at least a portion of which is located between an engine unit and a seat provided in a cover member. The engine unit is pivotally suspended on a body frame. A center axis of a cylinder extends obliquely upward from a crankcase and forwardly. Oil reservoirs and provided in a bottom of a crank chamber and a bottom of a portion of a transmission chamber located in a front portion of a transmission case, respectively. The oil reservoirs are communicated with each other by a communication path. A bottom surface of the transmission chamber in the portion in which portion the oil reservoir is provided is located downward of the bottom surface of the portion rearward of the oil reservoir of the transmission chamber.

Abstract: An engine having an engine case on one side of which a V-belt type of continuously variable transmission is provided, the CVT being placed in a transmission case and constituted that a V-belt is routed around a drive pulley and a driven pulley, the drive pulley being attached to one end of a crankshaft, the driven pulley being attached to one end of a transmission shaft parallel to the crankshaft, characterized in that the crankshaft is supported for free rotation with the engine case, one end of the crankshaft is projected in cantilever fashion from the engine case into the transmission case, the drive pulley is attached to the projected portion, and the transmission case is made as a component separate from or independent of the engine case and supported with the engine case so that a space is present between the engine case and the transmission case.

Abstract: Improved cooling capacity for a V-belt continuously variable transmission that is compatible with miniaturization of a vehicle body cover is provided in a saddle-ride type vehicle. A concave-shaped space recessed downward is compartmented forward of a seat by a vehicle body cover. An engine unit is supported by the vehicle body frame below the concave-shaped space. The engine unit includes a transmission case formed with a belt chamber in which a V-belt continuously variable transmission is accommodated. An intake duct defines an air passage communicated to the belt chamber. The intake duct is arranged between the transmission case and a leg shield.

Abstract: A downsized power unit equipped with a clutch operation-assisting device that reduces operation force of a clutch lever. The clutch operation-assisting device includes a push shaft and a first rotation plate that is rotatably supported by a support plate and connected to a clutch wire, and slides the push shaft by rotation. The first rotation plate and a second rotation plate are connected by gear. The second rotation plate is rotatably supported by a bearing member fixed to the support plate. A spring unit that provides assisting force in a direction to disengage a friction clutch is connected to the second rotation plate by pin. The spring unit, as seen from a shaft direction of the push shaft, is disposed so that an extension direction of an auxiliary spring does not pass through a rotation center of a pressure plate.

Abstract: In an engine unit of a straddle type vehicle, a V-belt-type continuously variable transmission (CVT) has a secondary sheave shaft 62 that rotates with a clutch housing of a centrifugal clutch. The secondary sheave shaft is supported in a cantilever fashion via two bearings. The engine unit has a gear that rotates with a clutch boss. Cage-and-roller needle bearings, which are a type of needle bearing, are inserted between the secondary sheave shaft and the gear. In this manner, without enlarging the engine unit, abrasions and deterioration of a bearing inserted between a rotational shaft supported in a cantilever fashion and a body of rotation are prevented.

Abstract: In a stepwise automatic transmission, a mass is concentrated in a longitudinal direction thereof. The stepwise automatic transmission includes an input shaft, an intermediate shaft, an output shaft, a first clutch which is connected and disconnected in accordance with a rotation speed of the input shaft, first and second power transmission mechanisms, and a second clutch which is connected and disconnected in accordance with rotation speed of the intermediate shaft. The intermediate shaft is disposed rearward of the input shaft. When the first clutch is connected, the first power transmission mechanism transmits rotation of the input shaft to the intermediate shaft. The second clutch is provided on the intermediate shaft. When the second clutch is connected, the second power transmission mechanism transmits rotation of the intermediate shaft to the output shaft. A front end of the second clutch is located forward of a rear end of the first clutch as viewed from an axial direction of the input shaft.

Abstract: A motorcycle including a belt type continuously variable transmission (CVT) and having a reduced width. An engine unit includes an engine having a crank shaft, the belt type CVT, a clutch, an output shaft and a generator. The CVT has a primary sheave, a secondary sheave shaft and a secondary sheave. The primary sheave is on one side of the crank shaft and the clutch is on another side with respect to the secondary sheave on the secondary sheave shaft. The output shaft is on a side opposite to the clutch on the secondary sheave shaft. The generator is on the other side of the crank shaft. A center axis of rotation of the secondary sheave shaft is higher than a center axis of rotation of the crank shaft. Right and left footsteps are located behind a rear end of the rotation motor and under a lower end of the secondary sheave.

Abstract: A motorcycle having high durability and a large space below a seat includes an internal space at least a portion of which is located between an engine unit and a seat provided in a cover member. The engine unit is pivotally suspended on a body frame. A center axis of a cylinder extends obliquely upward from a crankcase and forwardly. Oil reservoirs are provided in a bottom of a crank chamber and a bottom of a portion of a transmission chamber located in a front portion of a transmission case, respectively. The oil reservoirs are communicated with each other by a communication path. A bottom surface of the transmission chamber in the portion in which portion the oil reservoir is provided is located downward of the bottom surface of the portion rearward of the oil reservoir of the transmission chamber.

Abstract: In a motorcycle having a V-belt type continuously variable transmission, a resin washer made of a nylon resin is interposed between a boss fixed to a moving sheave half of a secondary sheave and a spring bearing member. The boss contacts the spring bearing member through the resin washer, whereby the moving sheave half is restricted to a Top position, in which a spacing between it and a stationary sheave half becomes maximum. In this manner, the maximum speed is not changed by exchange of the V-belt, the V-belt does not slip or become considerably abraded or deteriorated, and noise generation is suppressed.

Abstract: Abrasion of a V-belt in a belt type continuously variable transmission accommodated in an engine unit of a motorcycle is suppressed. A V-belt wound around and contacting a primary sheave and a secondary sheave 72 is at least partially formed from a resin. A plurality of grooves aligned at a predetermined pitch in a radial direction are formed on sheave surfaces of the primary and secondary sheaves. The average pitch P(mm) of the grooves is P??0.08K×10?3+0.18, where K(Hv) indicates surface hardness of the sheave surfaces.

Abstract: A clutching system comprises a lever mechanism portion and a clutch mechanism portion. The lever mechanism portion comprises a push lever. The push lever comprises a cam surface. The clutch mechanism portion comprises a push rod. The push rod comprises a cam follower. A Belleville spring functions as a clutch spring. The cam surface and the cam follower are formed such that a lever ratio of the push lever at a pivot start position is larger than a lever ratio of the push lever at a pivot finish position. The Belleville spring is formed such that a force required to move the push lever at the pivot finish position is smaller than a force required to move to the push lever at the pivot start position.

Abstract: To enhance the durability of the V-shaped belt by allowing the strength and the heat-radiating property of the resin blocks to stand together at high levels in the V-shaped belt, which has a plurality of resin blocks and endless connecting members connecting the resin blocks. The V-shaped belt includes a plurality of resin blocks arranged in a direction and an endless connecting member that is impacted into the resin blocks and that extends in the arrangement direction of the resin blocks. Depressions are longitudinally and vertically formed in the upside and downside of the front surface and the rear surface of each resin block. The depressions are separated from the connecting member and are also separated from the lateral surfaces of the resin block.

Abstract: Wear of a V-belt and wear of sheaves in a belt type continuously variable transmission is compatibly prevented. A V-belt wound around a primary sheave \ and a secondary sheave is formed with a resin block belt. A sheave surface of the primary sheave is plated with chrome. The secondary sheave is made of stainless steel and is not plated with chrome. The sheave surface hardness of the secondary sheave is lower than the sheave surface hardness of the primary sheave.

Abstract: To enhance the durability of the V-shaped belt by allowing the strength and the heat-radiating property of the resin blocks to stand together at high levels in the V-shaped belt, which has a plurality of resin blocks and endless connecting members connecting the resin blocks. The V-shaped belt includes a plurality of resin blocks arranged in a direction and an endless connecting member that is impacted into the resin blocks and that extends in the arrangement direction of the resin blocks. Depressions are longitudinally and vertically formed in the upside and downside of the front surface and the rear surface of each resin block. The depressions are separated from the connecting member and are also separated from the lateral surfaces of the resin block.

Abstract: An engine unit for a motorcycle that efficiently supplies lubricating oil to a clutch mechanism includes a connecting rod connected to a crank shaft, an oil pump, a clutch shaft having a clutch shaft body and a centrifugal type clutch, and a reduction mechanism having a reduction shaft in parallel to the crank shaft. The oil pump supplies lubricating oil to a connection of the crank shaft and the connecting rod. The clutch shaft body is arranged in parallel to the crank shaft. The clutch shaft body is closer to the crank shaft than is the reduction shaft. Lubricating oil supplied to the connection to scatter is led to the clutch shaft.

Abstract: A motorcycle having a belt type CVT and an engine unit in which an axial length of a cylinder is restricted. A body frame comprises a down frame extending vertically. The engine unit comprises a four-stroke engine, a belt type CVT, a clutch and a crank case. A cylinder is arranged rearwardly of the down frame with an axis thereof extending vertically. The clutch is provided between a secondary sheave shaft and an output shaft. The crank case is formed with an oil reservoir portion below a crank shaft to store lubricating oil. A rear end of the oil reservoir portion is rearward of a front end of a secondary sheave. An axis of the crank shaft is below an axis of the secondary sheave shaft.

Abstract: A riding type vehicle with improved cooling function of a V-belt continuously variable transmission and a compact body cover. A front side of a seat is partitioned with a space recessed to a lower side. The inside of a vehicle body cover is partitioned with a center tunnel. An engine unit is supported by a vehicle body frame on a lower side of the recessed space. The engine unit includes a transmission case having a belt chamber containing the V-belt continuously variable transmission. A footrest is arranged on an outer side in a vehicle width direction of the transmission case. An intake duct that guides air for cooling the V-belt type continuously variable transmission is disposed on an outer side in a vehicle width direction of the center tunnel and on an upper side of the transmission case.

Abstract: An engine comprises: a V-belt type continuously variable transmission on one side of an engine case, said CVT being provided with and housing in a transmission case a drive pulley attached to one end of a crankshaft, a driven pulley attached to one end of a transmission shaft parallel to said crankshaft, a V-belt routed around the pulleys, said engine case supporting said crankshaft and transmission shaft in a rotatable manner, and a generator attached to the opposite end of said crankshaft in said engine case; in which a filter chamber is disposed in the opposite side surface of said transmission case of said engine case in a depressed manner so as to overlap with at least a part of said generator in the crankshaft direction, and an oil filter for filtering lubricating oil is disposed in said filter chamber.