Abstract: A power unit of a motorcycle includes a case that contains a centrifugal clutch 34. A support member is disposed below the case to support first and second foot rests that extend laterally of the case. The case has an underside and at least one boss that extends downward from the underside at a location generally below the centrifugal clutch. The support member is secured to the at least one boss.

Abstract: A friction clutch includes a clutch housing having a friction plate, a clutch boss having a clutch plate, a pressure plate, a sub clutch, and a power-assist mechanism. An elastic member urges the pressure plate in a predetermined direction to press the friction plate and the clutch plate into frictional contact with each other when the clutch is engaged. The sub clutch includes a friction plate operatively disposed between first and second pressing plates. The power-assist mechanism receives torque from the pressure plate via the sub clutch when the clutch is disengaged and converts the torque into a force for moving the pressure plate in a direction which separates the pressure plate from a plate group.

Abstract: A centrifugal clutch for a vehicle includes a clutch housing having friction plates, a clutch boss having clutch plates, a pressure plate, and roller weights that press the pressure plate in a direction such that the friction plates and the clutch plates are brought into frictional contact with each other when the roller weights receive a centrifugal force. The vehicle power unit includes a main shaft which has an oil supply passage formed therein. The clutch includes a first oil supply path that supplies oil via the oil supply passage to the friction and clutch plates. The clutch includes a second oil supply path that supplies oil via the oil supply passage to the roller weights. The first and second oil supply paths are formed individually to allow independent adjustment of oil supply to each path.

Abstract: A clutch drive apparatus includes a clutch actuator and a drive force transmission mechanism that transmits the drive force of the clutch actuator to the clutch. The drive force transmission mechanism includes a case body and a case cover that is closed on the case body and supports the clutch actuator and a worm shaft. An opening is formed in the case cover to expose a marker member that determines a reference position of an auxiliary elastic body. A maintenance lid for covering the opening is mounted in a vehicle head pipe.

Abstract: A centrifugal clutch of a motorcycle has clutch housing which includes a friction plate, a clutch boss including a clutch plate, a pressure plate that pressure-contacts the friction plate with the clutch plate, a roller weight that receives a centrifugal force and presses the pressure plate toward a plate group side. The centrifugal clutch also includes an elastic body that constantly biases the pressure plate toward the plate group side to transmit a portion of a driving force from the clutch housing to the clutch boss even when the motorcycle engine is in an idling state. The elastic body may comprise a disc spring that biases the pressure plate toward the plate group and a coil spring that biases the pressure plate away from the plate group.

Abstract: A friction clutch includes clutch housing having a friction plate, a clutch boss having a clutch plate, a pressure plate, a sub clutch, and a power-assist mechanism. The power-assist mechanism receives torque from the pressure plate when the clutch is disengaged and converts the torque into a force for moving the pressure plate in a direction which separates the pressure plate from a plate group. A cam surface, which supports and guides one or more roller weights, is formed on the pressure plate. The one or more roller weights move outward in a radial direction by a movement amount according to the magnitude of centrifugal force and press the pressure plate toward the plate group with force according to the movement amount.

Abstract: A clutch drive device includes an actuator for generating a drive force for driving a clutch, a first solid of revolution, a mechanism for transmitting the drive force of the actuator to the clutch, and an assist spring unit having one end pivotally supported and another end abutting on the solid of revolution. An abutment structure in which the first solid of revolution abuts on the assist spring unit is configured so that an urging force of the assist spring does not act in a direction of rotating the first solid of revolution at least at one position in a play area in which the clutch is not disengaged even if the first solid of revolution rotates.

Abstract: A compact power unit for a vehicle having a clutch actuator is provided. The power unit includes a clutch actuator and a drive force transmission mechanism for transmitting the drive force of the clutch actuator to the clutch. The clutch actuator and the drive force transmission mechanism are arranged within a casing of the power unit. A drive shaft of the clutch actuator extends in the vertical direction. The drive force transmission mechanism includes a worm shaft coupled to the drive shaft of the clutch actuator, a first solid of revolution including a worm wheel portion which engages the worm shaft, a second solid of revolution which engages a gear portion of the first solid of revolution, and a ball cam. The ball cam converts torque from the second solid of revolution into a force which acts in the axial direction of a slide shaft of the clutch.

Abstract: A motorcycle is provided with a vehicle body, front and rear wheels, an engine and a power transmission mechanism for connecting the engine to the rear wheel. A centrifugal clutch and a transmission having a plurality of gears are arranged in the power transmission mechanism. A handle is provided on the vehicle body. An accelerator grip is provided on the right side of the handle and a clutch lever is provided on the left side. A shift pedal for changing the transmission gear ratio of the transmission and a side stand are provided on the left side of the vehicle body. A rear brake pedal for braking the rear wheel is provided on the right side of the vehicle body. The motorcycle is also provided with a rotation suppression mechanism for suppressing the rotation of the rear wheel at least when the engine is stopped.

Abstract: A saddle-type vehicle with improved cooling performance of a V-belt continuously variable transmission and a compact body cover. A motorcycle has a downward-recessed space defined by a body cover in front of a seat. An engine unit is supported by a body frame below the recessed space. The engine unit has a transmission case with a belt chamber for accommodating a V-belt continuously variable transmission. An air chamber communicates with the belt chamber through an air intake duct. The air chamber is disposed above the front part of an arm of the rear arm relative to a middle thereof in a front-rear direction.

Abstract: A motorcycle has a frame and a power unit. The frame comprises a main frame member extending rearward from a steering head pipe. The power unit comprises a drive source, power transmission devices attached to the output end of the drive source, and a casing that houses the power transmission devices and that is suspended from the main frame member. The casing of the power unit comprises a recess opening toward the main frame member. A boss is formed on the bottom of the recess and is suspended from the main frame member.

Abstract: A centrifugal clutch is provided with a clutch housing, a clutch boss, a plate group, a pressure plate, a roller retainer, a disc spring, a pressing body and a clutch release mechanism. The pressure plate is displaced on one side in the direction of an axis line and configured to directly or indirectly press the plate group and transition the same into a pressed-contact state. The disc spring extends in a direction of being inclined to the direction of the axis line from a first end portion toward a second end portion in a centrifugal direction. The first end portion of the disc spring is directly or indirectly fixed to the clutch housing. The second end portion of the disc spring directly or indirectly biases the roller retainer toward the plate group.

Abstract: A clutch structure, constructed without a one-way clutch, remains engaged until the input side rotational speed becomes relatively low. A pressure plate presses a group of plates directly or indirectly by moving in the direction of an axis, bringing the group of plates into a press contact state. An input side press body turns around the axis with the rotation of a clutch housing, presses the pressure plate to the side of the group of plates by centrifugal force generated during the turning, and moves in a direction away from the axis. A roller retainer presses the group of plates directly or indirectly by moving in the direction of the axis, bringing the group of plates into a press contact state. An output side press body turns around the axis with the rotation of an output side clutch member, presses the roller retainer to the side of the group of plates by centrifugal force generated during the turning, and moves in a direction away from the axis.

Abstract: A belt-type continuously variable transmission that prevents escape of noise generated by a resin block belt to the outside. The resin block belt is wound around a primary sheave and a secondary sheave. A transmission case defines a belt chamber accommodating the primary sheave, secondary sheave, and resin block belt. The transmission case includes an exhaust passage, intake passages, and a sound absorbing member. The sound absorbing member is attached to an inner wall of the exhaust passage in a position to collide with sound waves traveling through the exhaust passage. The sound absorbing member has a sound absorbing surface crossing an extending direction of the exhaust passage.

Abstract: A noise preventing means for a motorcycle including a belt type continuously variable transmission using a resin block belt. An end of an intake duct for inducting cooling air into a belt chamber inside a transmission casing is connected to a front half part of the transmission casing. The intake duct extends upward from the transmission casing, then curves rearward, and extends rearward passing over a seat pillar. An air chamber is connected to a rear end of the intake duct. The intake duct has a curving part curving around the seat pillar.

Abstract: A noise suppressor for a straddle-type vehicle provided with a belt type continuously variable transmission having a resin-block-type belt. A portion of an air passage for guiding air to a belt chamber is formed in a closed casing. The closed casing includes a dish-shaped first casing member and a dish-shaped second casing member. An inlet port and an exhaust port are formed in the second casing member. Partition walls in the form of curved plate pieces are formed in the first casing and second casing members. Air flow paths formed by the partition walls are U-shaped, thereby forming a serpentine flow.

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 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: 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.

Abstract: An engine has a built-in continuously variable transmission (CVT) interconnecting a crankshaft connected through a connecting rod to a piston and a transmission shaft to which the rotation of the crankshaft is transmitted for changing speed between both of the shafts. A driven pulley and a clutch are disposed on the transmission shaft. A balancer shaft to which the rotation of the crankshaft is transmitted and the clutch are disposed in an overlapping positional relationship with each other in the direction of the crankshaft.