The 125cc V4 machine that won two consecutive World titles
This model was a further development of the 125cc liquid-cooled V-4 RA31, which was the 125cc model scaled down from the 250cc RD05. The RA31 was a machine that inherited the winning formula of Yamaha racers employing the rotary disc valve intake, forced lubrication with oil pump (used together with oil-mixed gasoline fuel) and the feather bed type double-cradle frame. In the opening round of the 1967 season it scored a debut win and went on to collect 10 wins on the season ridden by B. Ivy. That brought Ivy the Rider's title and Yamaha the Manufacturer's title. In 1968, it evolved into the RA31A with the same advances in weight and size reduction as the RD05A and won a second consecutive Rider's title, this time in the hands of P. Read.
- Capacity - 124cc
- Max Power - 40PS