Patent ID: 7527119

Claim:
A swing arm support structure in a motorcycle, the motorcycle comprising: a vehicle body frame; a rear wheel; a power unit mounted on the vehicle body frame, said power unit including a power unit case, an engine and a transmission system, said transmission system including an output shaft for imparting power to the rear wheel and being adapted to decelerate the output of said engine and transmit the decelerated output to the output shaft, said transmission system further including a drive sprocket for transferring power from said output shaft to said rear wheel, the drive sprocket being fixed adjacent to an outer end of the output shaft; and a swing arm extending between the rear wheel and the vehicle body frame, the swing arm comprising a front portion which includes forwardly extending first and second support arm portions provided on the right and left sides of the front portion, and a rear portion which supports the rear wheel through an axle, wherein said swing arm support structure comprises: a first pivot shaft and a second pivot shaft, the first pivot shaft being cylindrical and oriented coaxially with said output shaft, the second pivot shaft oriented coaxially with the first pivot shaft, and said first support arm portion is pivotally supported by said power unit through the first pivot shaft, and said second support arm portion is pivotally supported by said power unit through the second pivot shaft, the first pivot shaft extends through said first support arm portion, and a flange portion is formed on the first pivot shaft, said flange portion: extending radially outwardly at least partially up to an outer edge of said power unit case, projecting from an end portion of said first pivot shaft, the end portion located adjacent said power unit case, and being removably attached to said power unit case, wherein said output shaft extends through and is supported by said first pivot shaft, the outer end of the output shaft projects outwardly from said first support arm portion, and the drive sprocket is fixed adjacent to the outer end portion of the output shaft at a position such that the drive sprocket resides outside said first support arm portion.