Abstract: To arrange a steering damper behind a head pipe in a compact manner while suppressing the influence of the steering damper on an intake duct which penetrates the vicinity of head pipes of a vehicle body frame. A steering damper is arranged between left and right main frames of a vehicle body frame and, at the same time, is arranged above or below an intake duct which penetrates the vicinity of a head pipe of the vehicle body frame.

Abstract: To easily secure a welding length when an opening is formed at a portion in the vicinity of a joint portion between a head pipe portion and a main frame portion. A front opening penetrating through a vehicle body frame across a head pipe portion and a main frame portion. A rib extending across the front opening along a front parting plane of the vehicle body frame. The rib being divided along the front parting plane and the edge portions of the divided rib portions opposing the outer periphery of the main frame portion are integrally joined.

Abstract: An intake duct structure having an intake path extending forwardly from a cleaner box, penetrating through an area near a head pipe of a vehicle body frame, and opening at a front end portion of a front cowl. During low speed operation of the engine, an intake valve closes a main intake path MR from a front end intake port and opens a sub-intake path SR from a lower portion intake port. On the other hand, during high speed operation of the engine, the intake valve opens the main intake path MR and closes the sub-intake path SR. The lower portion intake port opens forward of a head pipe inside a front cowl and obliquely downwardly toward the rear. With this arrangement, entry of rainwater into the intake path can be minimized during low speed operation of the engine.

Abstract: To easily secure a welding length when an opening is formed at a portion in the vicinity of a joint portion between a head pipe portion and a main frame portion. A front opening penetrating through a vehicle body frame across a head pipe portion and a main frame portion. A rib extending across the front opening along a front parting plane of the vehicle body frame. The rib being divided along the front parting plane and the edge portions of the divided rib portions opposing the outer periphery of the main frame portion are integrally joined.

Abstract: An intake duct structure having an intake path extending forwardly from a cleaner box, penetrating through an area near a head pipe of a vehicle body frame, and opening at a front end portion of a front cowl. During low speed operation of the engine, an intake valve closes a main intake path MR from a front end intake port and opens a sub-intake path SR from a lower portion intake port. On the other hand, during high speed operation of the engine, the intake valve opens the main intake path MR and closes the sub-intake path SR. The lower portion intake port opens forward of a head pipe inside a front cowl and obliquely downwardly toward the rear. With this arrangement, entry of rainwater into the intake path can be minimized during low speed operation of the engine.

Abstract: To arrange a steering damper behind a head pipe in a compact manner while suppressing the influence of the steering damper on an intake duct which penetrates the vicinity of head pipes of a vehicle body frame. A steering damper is arranged between left and right main frames of a vehicle body frame and, at the same time, is arranged above or below an intake duct which penetrates the vicinity of a head pipe of the vehicle body frame.