Abstract: A power unit support structure of a motorcycle having a power unit and a frame structure including a support member having a rear end portion terminating in conjunction with the power unit which comprises an elongated swing member positioned between the power unit and the rear end portion of the frame structure and having at one end thereof pivotally connected with the power unit. A pivot support assembly is provided on the rear end portion of the frame structure for pivotally supporting the elongated swing member. A pair of rigid arms is provided each of which is fastened onto the swing member at one end thereof. The rigid arms are associated at the other ends thereof with the rear end portion of the frame structure by way of damper means for dampening the swing motions of the swing member.

Abstract: There is disclosed a cover structure in a power transmission device comprising a casing having an open side, a driver shaft rotatably supported by the casing, a driven shaft rotatably supported by the casing and drivable by the driver shaft, a power transmission mechanism housed in the casing for transmitting rotative power from the driver shaft to the driven shaft, a starter mechanism housed in the casing and engageable with the driver shaft for starting an engine, and cover means covering the open side of the casing. The cover means comprises a plurality of cover members, a cover member which supports the starter mechanism being securely coupled to the casing, the remaining cover member or members being coupled to the casing through a resilient member or members.

Abstract: A vibration isolating pipe wherein slits are cut along the axis of the pipe and the friction of the slit surfaces absorb vibrations. Applications are made to a motorcycle body frame and a motorcycle exhaust pipe.

Abstract: A power-unit support structure of a motorcycle having a power unit and a frame structure including a tubular member having a hollow rear end portion, comprising a rigid bracket member secured to the tubular member and positioned in the vicinity of the rear end portion of the tubular member, a first pivot assembly positioned between the power unit and the tubular member and pivotally movable about an axis fixed with respect to the frame structure, a second pivot assembly mounted on the power unit and pivotally movable about an axis fixed with respect to the frame structure and parallel with the axis of pivotal motion of the first pivot assembly, rigid connecting members providing connection between the first and second pivot assemblies, a damper assembly rigidly connected to the first pivot assembly and elastically engaging the rear end portion of the tubular member.

Abstract: A power unit suspension system wherein a vehicle frame and a front lower portion of a power unit are connected with each other through a link rotatable about its front and rear pivots. An elastic body is provided between the link and the power unit. Rotational loads due to the power unit weight and rear cushion reaction acting on the link from the power unit side are elastically supported and converted into a moment of rotation.

Abstract: A swinging power unit type motorcycle having an engine swingably hung and pivoted on a body frame, and a pair of plates forming a rear fork connected to the engine. A chain drive transmits power from the engine to a reduction gearbox which incorporates the rear wheel axle and is supported between the rear fork. Shock absorbers are connected between the body frame and the rear fork. The engine, rear fork, rear wheel axle, chain drive, and reduction gearbox are interconnected to swing as a unit relative to the body frame.