A main pipe of a motorcycle is enhanced in stiffness to stably support an
engine. The main pipe includes an intermediate pipe extending above the
engine in a longitudinal and substantially horizontal direction, a front
pipe extending forwardly downwardly of the engine from a front end of the
intermediate pipe, and a rear pipe extending rearwardly downwardly of the
engine from a rear end of the intermediate pipe. The rear pipe is curved
arcuately in a manner to go around a pivot shaft forwardly downward from
a rear side thereof and the engine is connected to a lower end side of
the rear pipe.