Yamaha's first pure race machine
This was Yamaha's first race machine and it was built specifically for participation in the 2nd Asama Highlands Race. It featured a 250 cc air-cooled 2-stroke, 2-cylinder engine mounted on a newly designed double cradle type frame. It was designed in YD-A and YD-B versions with different bore x stroke specs of 54x54mm and 56x50mm respectively. Even at 250cc its weight was a mere 100kg, which was about 20 kg lighter than the rival machines in the same class. With the resulting superiority in handling and acceleration, Yamaha riders swept the podium places. In appearance, it was distinguished by its "dolphin cowl." In 1958, Fumio Ito competed successfully in the Catalina GP in the U.S. with a scrambler type modification of this YD Racer. Single-cylinder 125cc versions were introduced at the same time as the YA-A and YA-B.
- Capacity - 247cc
- Max Power - 26PS