Abstract: A mold and a die-cast manufacturing method for the die-cast product, in which a main frame which is contiguously formed with a head pipe constitutes a portion of a hollow light-weight-metal-made vehicle-body frame. The mold includes a core for forming an inner space of the hollow vehicle-body frame. The core includes a core body and a plurality of splints mounted on the core body, the splints having approximately elliptical cross-sectional shapes. The long axes direction of ellipses of the splints are set parallel to a mold split surface of the mold. As a result, measurement of the positional accuracy of the splints is facilitated, a clearance between the splint and the mold can decrease by increasing the dimensional accuracy of splint mounting portions of the mold based on sizes of the splints, and the frame can be manufactured with high dimensional accuracy.

Abstract: A mold and a die-cast manufacturing method for the die-cast product, in which a main frame which is contiguously formed with a head pipe constitutes a portion of a hollow light-weight-metal-made vehicle-body frame. The mold includes a core for forming an inner space of the hollow vehicle-body frame. The core includes a core body and a plurality of splints mounted on the core body, the splints having approximately elliptical cross-sectional shapes. The long axes direction of ellipses of the splints are set parallel to a mold split surface of the mold. As a result, measurement of the positional accuracy of the splints is facilitated, a clearance between the splint and the mold can decrease by increasing the dimensional accuracy of splint mounting portions of the mold based on sizes of the splints, and the frame can be manufactured with high dimensional accuracy.

Abstract: To avoid exertion of an external force on a fuel tank as much as possible. A mounting structure of a fuel tank for a motorcycle provides a fuel tank that is disposed between a pair of left and right frame members of a vehicle body frame and the fuel tank is mounted on the vehicle body frame at a first mounting portion and second, third, and fourth mounting portions. The fuel tank is mounted at each of the mounting portions via a plurality of tubular resilient bodies. The first mounting portion allows resilient support in the fore-and-aft direction and in the vertical direction of the vehicle and limits the lateral movement. The second, third, and fourth mounting portions allow resilient support in the fore-and-aft direction and in the vertical direction of the vehicle.

Abstract: A seat rail extending rearwardly from a vehicle body frame to support a seat. The seat rail is formed of a left-and-right two-split cast product having a substantially flat upper surface and, at the same time, includes cross members. These cross members can be mounted later using bolts. The seat can be arranged above the seat rail and the cross members and, at the same time, a seat engaging member which engages the seat with the cross member can be formed on the cross member. The seat rail is constituted of the left and right seat rails which are divided with respect to a vehicle width center. This seat rail structure provides for simple manufacture and assembly.

Abstract: To avoid exertion of an external force on a fuel tank as much as possible. A mounting structure of a fuel tank for a motorcycle provides a fuel tank that is disposed between a pair of left and right frame members of a vehicle body frame and the fuel tank is mounted on the vehicle body frame at a first mounting portion and second, third, and fourth mounting portions. The fuel tank is mounted at each of the mounting portions via a plurality of tubular resilient bodies. The first mounting portion allows resilient support in the fore-and-aft direction and in the vertical direction of the vehicle and limits the lateral movement. The second, third, and fourth mounting portions allow resilient support in the fore-and-aft direction and in the vertical direction of the vehicle.

Abstract: A seat rail extending rearwardly from a vehicle body frame to support a seat. The seat rail is formed of a left-and-right two-split cast product having a substantially flat upper surface and, at the same time, includes cross members. These cross members can be mounted later using bolts. The seat can be arranged above the seat rail and the cross members and, at the same time, a seat engaging member which engages the seat with the cross member can be formed on the cross member. The seat rail is constituted of the left and right seat rails which are divided with respect to a vehicle width center. This seat rail structure provides for simple manufacture and assembly.

Abstract: To attach right and left arms of a rear fork reliably to a pivot portion and right and left pivot supports without undue attachment loads imposed thereon. A motorcycle having a rear fork attachment structure includes an engine disposed substantially centrally in a vehicle body, right and left arms of a rear fork extending over right and left sides of a pivot portion of the engine, right and left pivot supports depending from a vehicle body frame extend over right and left sides of the right and left arms, and the left pivot support, the left arm, the pivot portion, the right arm, and the right pivot support coupled together by a single pivot shaft. Furthermore, the right and left pivot supports have adjustment bolts having respective pivot shaft insertion holes, and the adjustment bolts adjust distances between the right and left arms and the right and left pivot supports.