In the United States, professional motocross riders race production-based machines. In Europe, in the World championship, pros race full factory prototypes (if they are lucky enough to ride for a factory). Yamaha has signed four-time World champion Stefan Everts to race a four-stroke in the 500cc class in Europe next year.
Everts, and one of his teammates, will race a four-stroke Yamaha with increased displacement (more than 426cc) and a completely new crankcase, among other modifications. The exact displacement of the works motor is unknown, but it may indicate the displacement of next year’s production machine from Yamaha. Frequently, factory prototypes raced in the World championship result in production machinery the following year.
With the YZ400F/426F ending its fourth year of production, expect major changes from Yamaha to this model next year. Yamaha undoubtedly wants to stay ahead of Honda’s efforts to challenge in the big-bore four-stroke motocross market. Honda is racing a prototype 450cc machine this year, which is expected to become a production machine in September. Yamaha was the pioneer among the Japanese manufacturers in the four-stroke motocross market, and it will be anxious to stay one step ahead of Honda.