The second Asama Highlands Race took place in autumn 1957. Yamaha chose to compete in both the 125 cc and 250 cc classes. It developed race bikes based on the YA1 and YD1 with the goal of following up on its success in the previous race with more victories. Two types of engines with differing bore stroke specifications were designed for both the YA1 and YD1. The YA-A and YA-B versions of the YA Racer were ridden in the race along with the YD-A and YD-B versions of the YD Racer.
As in the first Asama Highlands Race, Yamaha dominated, taking first, second, and third places in the 250 cc class. In the 125 cc class as well, the company captured first and second places. Motivated by these victories, Yamaha decided to develop the first domestically produced sport model. The company would produce a commercially available motorcycle that put emphasis on sportiness. It would be based on the YD Racer, which distinguished itself at the Asama Highlands Race.
The design objectives for the new model were clear. If Yamaha was going to produce a sport bike, it had to be acceptable worldwide. It was also preferable that the bike be suitable for touring. Based on this, the company decided to provide an ample variety of kit parts and aimed to make the bike compatible with both on-road and off-road racing.
The 250 cc 2-cylinder, 2-stroke engine was fitted with a 2-barrel carburetor, the transmission featured five speeds, and an integrated instrument panel with a speedometer, tachometer, and trip odometer was incorporated into the headlight nacelle, which had a small wind protector. Each of these features was a first for a domestic motorcycle. Moreover, it featured a novel two-tone color scheme with cream white and orange pearl metallic which, along with the bike’s styling, was befitting a motorcycle that would go on to become a classic in the history of Japanese motorcycles.
Launched as the 250S, the motorcycle was greeted with much fanfare when it was put out on the market in July 1959. As a high-speed sport bike with 20 horsepower and a top speed of 140 kph, it was built for speed and nimble handling. Its performance led it to garner the overwhelming support of sport bike riders. After 3,000 units of the bike had been shipped, its name was changed to the YDS1.
The YDS1, Japan’s first full-fledged sport bike, served as the original form of Yamaha’s 2-stroke twin sport bikes, and while various changes took place over the years, it continued to provide the foundation for numerous sport bikes that came out later.