A body frame for a motorcycle includes a main frame having a reinforcing member, which is a forged product, and a portion that requires a high strength against a shock load transmitted from a road surface A pair of sidewalls and a connecting wall for connecting the sidewalls are also provided The sidewalls create spaces opened outward in cross-section such that the connecting wall has an external face positioned in the portion that requires high strength

Body frame for motorcycle

A vehicle body frame for a motorcycle comprises a main frame (2a) provided for mounting thereon an engine unit (11) and supporting a front fork (4) and a rear arm (7). The main frame (2a) is structured by a head pipe unit (20) extending from a head pipe (3) backward and diagonally downward relative to the vehicle while spreading vertically; a down frame (21) connected to a lower end front portion of the head pipe unit (20); and right and left rear arm brackets (10) installed between and connected to a rear end portion of the down frame (21) and a lower end rear portion of the head pipe unit (20). The head pipe unit (20) is a die-cast aluminum unit, and the down frame (21) and the right and left rear arm brackets (10) are forged aluminum units.

Vehicle body frame for motorcycle

A frame structure for a motorcycle includes a front fork which journals a front wheel and that is capable of being steered and supported by a head pipe. Front end portions of a pair of right and left pipe members are connected contiguously to the head pipe and extend downwardly and rearwardly from the head pipe. The pair of right and left pipe members each have a substantially prismatic cross sectional shape and are each bent at their longitudinally intermediate portions so as to be outwardly convex with respect to the sides of the motorcycle frame. An engine is disposed between lower portions of both pipe members in an engine mounting space. The present invention narrows the distance between the upper portions of the right and left pipe members and effectively increases the space between the lower portions of the pair of right and left pipe members.

Frame structure in motorcycle

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.

Vehicle body frame, die-cast product, mold for die-cast product and die-cast method

A motorcycle frame, and motorcycle with the frame as disclosed. There is disclosed a motorcycle frame having tubes extending away from a steering head tube in a three-dimensional trellis composite assembly of frame main tubes, interconnected by frame struts, paired upper and lower frame main tubes oriented, along at least a portion of their lengths, substantially parallel to each other. A single tube is oriented parallel to the lower frame main tubes, and arranged between the upper frame main tubes and the steering head tube.

Motorcycle frame and motorcycle engineered therewith

PURPOSE:To improve rigidity, by a method wherein, when a head pipe is formed by means of curved parts located to the fronts of division frames on both sides, joint parts surrounding a ring member are integrally welded together in a state that the ring member is engaged between the curved parts. CONSTITUTION:A title frame is formed with division frames 10 and 20 in the shape of a square pipe on both sides which are molded by aluminum casting. Curved parts 11 and 21 approximately in a semiarcuate in cross section are formed in a protruding manner to the tips of the division frames 10 and 20, and the two curved parts 11 and 21 are mated to each other to form a head pipe H. The division frames 10 and 20 are extended rearward toward an oblique downward position, and a down pipe 15 or 25 and a rear pipe 16 or 26 are branched from a part of the division frame. Upper and lower ring members 30 and 32 are engaged with the upper and lower inner parts of curved spaces 13 and 23 of the division frames 10 and 20, and are welded to joint parts between the curved parts 11 and 21, upper and lower notch parts 12a, 12b and 22a, 22b, and the division frames 10 and 20.

Saito Hiroshi

Papers

Frame for motorcycle