Rainey wins his first World GP title
Handling stability was improved on this model by introducing dimension changes including a head pipe position that was closer to the rider and a lower caster angle. The power output was also increased to 155PS from 150PS for the previous year's model. On this machine Rainey won seven rounds to claim his first World GP title. This contributed to Yamaha's 6th Manufacture's championship. This OWC1 would also be the base machine that for the factory engine that Yamaha would sell to privateer constructors along with chassis data to such as Harris and ROC Yamaha to stimulate the GP500.
- Capacity - 499cc
- Max Power - 155PS
1st: 7 Wayne Rainey Team Marlboro Yamaha Roberts Japan, USA, Italy (Nations), Yugoslavia, Belgium, Sweden, Czechoslavakia