The trick, prototype motocross machines campaigned by Yamaha in Europe are frequently harbingers of production models. For example, in 1999, Yamaha raced a four-stroke in the open-class displacing 426cc, and the production YZ426F was introduced during the next model year.
Last year, Yamaha developed a unique, aluminum motocross frame. It is unique because it is aluminum, but mimics the design of the YZ frames (semi-double-cradle). Yamaha claims it provides the best of both worlds, i.e., the light weight of aluminum with enhanced rider feedback and weight balance found in the conventional, steel frame. Stefan Everts and his teammates are racing the open-class this year with that same frame, and this could indicate production YZs of this design will follow in model year 2002.
Additionally, the displacement of Yamaha’s four-stroke motocrosser is “over 500cc” which necessitated an all-new crankcase design that might see production as well. Perhaps, Yamaha will race a large capacity four-stroke in the final season before the AMA restricts four-strokes to 450cc. Honda has also indicated that its four-stroke motocrosser will be raced with a displacement that exceeds 450cc in competition this year.