PURPOSE: To reduce the width of a motorcycle, and to smoothen the flow of cooling air in the motorcycle where a discharge pipe swelling dia. part is arranged vertically at the downstream side by arranging a radiator at the front of a down tube while arranging it to be overrupped with the pipe, and setting same on the opposite side of the swelling part in an offset manner.

CONSTITUTION: A radiator 4 is arranged such that it is overruped with the width distance between small dia. pipes 12, 12 at the front of double-tube type two small dia. pipes 12, 12. In this case, it is arranged on the opposite side of a discharge pipe swelling dia. part 53 disposed on the side of the pipes with respect to the center of the width of motorcycle. It is thus possible to reduce the width, smoothen the flow of cooling air and increase the stroke of the front wheel.