Honda TRX250R - Rise of The Aftermarket

Rise of The Aftermarket

While raced in mostly stock form in its earliest years, by the time production rules were initiated only about six of the TRX250R's components had to be purchased from Honda . According to CT Racing’s Allen Knowles, “More aftermarket parts have been made for the 250R than any other ATV.” “Sixty Percent of my business was based on the R, compared to the next highest Banshee, at fifteen percent. With only the Banshee, I would have starved” said Wayne Hinson of Hinson Racing.

Initially, items that were subject to the most abuse from racing were the first to be remade. Originally made of die cast aluminum, the clutch basket was found to be weak when power was increased or subjected to race conditions. The first aftermarket clutch basket was a machined steel piece campaigned by Gary Denton in 1989. Wayne Hinson, who would later found worldwide clutch component manufacturer Hinson Racing, designed the clutch basket and later changed it to billet aluminum in 1991.

A regular trend that started on the Fourtrax that would not carry over to the four strokes was the use of aftermarket frames. Stock frames on most mass produced quads are made of mild steel and, though suitable for recreational use, will quickly develop cracks when raced. Without new quads available after the 1989 model year, stronger replacement frames for racing were soon needed. The first aftermarket frame for the 250R was made by dirt track motorcycle chassis builder, C&J in 1991 for CT Racing. This frame was a direct replacement for the original, maintaining stock suspension geometry. The first altered geometry frame was introduced by JP Racing a short while later. This design brought the front suspension mounts in one inch on each side, allowing the use of longer suspension arms in competition, which increased wheel travel and improved the ride qualities. By 2003, a myriad of aftermarket frames could be had from numerous manufacturers in both stock and altered geometry, made of steel and aluminum. Lone Star Racing produced a titanium frame, but AMA rules prevented its use in competition.

Though Honda was initially concerned with reliability and detuned the original 250cc motor, with the release of the Pro-X (pro-cross) cylinder and head in 1994, the 250R’s displacement could be increased well into the 300cc range by changing the cylinder alone. Additionally, this and other aftermarket cylinders offered advanced port layout for more tuning options. With modifications to the transmission cases, later aftermarket cylinders and crankshafts permitted engine displacements to reach 500cc’s. The last version of the Pro-X cylinder, as well as others, also added an exhaust operated powervalve, a feature that was left off the 250R but used almost universally by the competition, as well as in Two-Stroke motocross bikes since the mid-eighties.

Although great increases in displacement and power became possible, the TRX250R’s transmission did have its limits, and gear strength became an issue. To allow for the larger engines a joint venture between Baldwin Motorsports and Timken Bearing, in the 90's, produced a set of stronger aftermarket gears. These gears permitted engines over 330cc's to be reliably raced. The TRX250R is the only quad for which such a product was made.