1990 AMA National 125 Motocross champion, Guy Cooper, at close to 40 years old, will race the AMA 250 Outdoor National Motocross championship series this year, beginning next month in San Bernardino, aboard a KTM 540 four-stroke reportedly making over 70 horsepower. The specially built 540 (basically, a KTM 520SX with lots of trick parts, including a big bore, high compression piston), to give you some perspective, should make roughly 15 horsepower more than the most powerful 250cc factory two strokes. Lots more torque, too.
Cooper reportedly calls the bike “the best” he’s ever ridden, and he has had factory machinery before. Although, at his age, Cooper won’t be a title threat, he sure could pull plenty of holeshots and spend time mixing it with the leaders.
What is most interesting about this story is the fact that a 70 plus horsepower motocross bike (weighing less than 230 pounds) is controllable and rideable by a guy roughly 40 years old. This is the beauty of the four-stroke power delivery in dirt bikes. The fatigue factor is dramatically reduced (a two stroke with this much of power would wear out the youngest, most fit motocrossers).
With the AMA set to limit four-stroke engine capacity to 450cc next year (for the 250cc two-stroke class), maybe a new “open class” will emerge for the mega four-stroke machines. If four-strokes can be this powerful, and this much fun, maybe it will happen.
