A body frame for a motorcycle is disclosed wherein a head pipe is provided for pivotally supporting a front fork. A main pipe extends from the head pipe, the main pipe is curved to extend rearwardly and downwardly. A pivot unit is secured to the downwardly extending portion of the main pipe for pivotally supporting a rear swing arm thereon. The main pipe includes a transversely elongated cross section and extends in a vertical plane including a longitudinal axis of the motorcycle. The body frame includes a seat rail for supporting a seat, the seat rail is connected to a rear portion of the main pipe and includes a transversely elongated cross section extending in a vertical plane including the longitudinal axis of the motorcycle. Down tubes are provided for supporting a forward portion of an engine. The down tubes connected to the main pipe include a transversely elongate cross section and extend downwardly from the head pipe in a vertical plane including the longitudinal axis of the motorcycle.