Having started out as one of the last companies to enter the Japanese motorcycle industry and achieving success with its first models YA-1 (125 cc) and YC-1 (170 cc), Yamaha Motor was ready for its next challenge. That would be the development of the 250cc YD-1.

It is a well-known fact that Yamaha's YA-1 was created by studying the structure of the German maker DKW's representative model RT125 and copying its chassis. But, Yamaha was not the only one. Those were times when most of the other Japanese makers were also copying the front-running motorcycle models of the advanced German makers and introducing one new model after another based on these German machines. This was surely a necessary step along the way to postwar recovery for the domestic Japanese motorcycle industry.

As Yamaha Motor began planning its first 250 cc bike, the model chosen as its target was the MB250 of the German maker Adler. Powered by a 2-cylinder 2-stroke engine, this machine was a masterpiece of design and engineering that had won a strong reputation among European riders. At Yamaha Motor it had been decided to copy the basic engineering specs of this model and add some unique exterior design touches.

It was the company's ambitious young engineers, however, who would object to this plan. The success of the YA-1 and YC-1 had planted in them a seed of confidence in their abilities and they were anxious to test themselves, to see what they could really do. They also believed that until they created a completely original machine, there would be no truly significant advance in the motorcycle design and manufacturing technologies of Yamaha or the Japanese motorcycle industry as a whole. And it was this purely motivated desire of the engineers to build not a copy, but a proud Yamaha original that finally changed the company's policy.

Thus began the job of building a motorcycle from scratch. And it brought with it the trials of wrenching the Japanese motorcycle industry from its mode of copying into the new realm of true creation. And, for these engineers with no previous experience of building a product completely from step one, the first problem they encountered was that of creating the grand design for work process itself.

If the Yamaha originality expressed in the YD-1 were to be summed up in one point, it would be building a 250 cc bike for the Japanese user. The average size of a German rider and a Japanese rider was clearly different. Certainly Japanese riders needed a bike that fit their body size, and it was also decided that there was no need for more power than that necessary to run comfortably at the speed limit on Japanese roads carrying a normal load.

One of the most impressive visual features of the final YD-1 was the prominence of its fuel tank, which would later be likened to images like a tea urn or a steel helmet. But, there was in fact a structural necessity behind its distinctive shape.

Once the basic overall layout of the machine had been decided, including the seat height, wheelbase and the shapes of the handlebars and the seat, it was discovered that the space for the fuel tank lacked both the length and the width to get the 15-liter volume the original plans called for. At the time 15 liters was the standard volume for a 250cc model and that was one spec that the engineers wanted to meet. To get that desired volume, it was natural to expand the width of the tank, but it was also decided to expand the shape vertically. The result was a unique form that looked like the usual front-rear layout of the tank had been reversed. What made this tank even more impressive was probably the bold decision to color it dark brown, a color never before seen on a motorcycle. This was probably one of the reasons that the YD-1 would later be referred to as the first Japanese motorcycle to incorporate what was at the time the new concept of "industrial design."

Drawing on the example of the Adler MB250, the YD-1's engine was a 2-cylinder design. Building a 2-cylinder engine was a new challenge for Yamaha and when it went into the design stage no other Japanese maker had yet built a 2-stroke 2-cylinder engine. Although the Adler was used as a model, components like the clutch assembly and dynamo were given original Yamaha designs in order to create a more compact engine. In the end, the Yamaha engineers created a high-performance engine that was low in vibration and pumped out an impressive 14.5 horsepower.At the time of the YD-1's debut, the trend in Japanese 250cc models was toward a greater sense of weight and presence. But, with the appearance of the compact YD-1, with its sporty engine performance, that trend would be reversed. Looking back now, we realize that the effect of the YD-1 was tremendous in setting the Japanese motorcycle industry on a course that would define its future.

The first YD-1 came off the production line on February 11, 1957, and President Kawakami personally stamped the serial number on its engine. This was a tradition that started with the first YA-1, but the YD-1 would be the last model to be stamped by the president¡s hand. An official press introduction for the new YD-1 had been planned to take place on March 20th at the Ministry of International Trade and Industry¡s test course in Tokyo. But, to everyone¡s surprise a photo of the new model hit the press in advance of the official release when a newspaper journalist for the automotive industry happened to catch President Kawakami and two other Yamaha managers touring the 300 km from Hamamatsu to Tokyo on three YD-1s prior to the press event.

The YD-1 went on sale as scheduled in May of that year and was also displayed in the 4th All Japan Motor Vehicle Show held in Tokyo¡s Hibiya Park. By the time of this show, the motorcycle magazines had already reviewed the YD-1 and given it high marks for its unique styling, light handling and lively acceleration and speed, and thanks to this it is said that there was always a crowd of excited fans around the YD-1 display. At the time in Japan motorcycle were still primarily used for utility purposes like carrying luggage. However, it was sports use that surely came to the mind of everyone who saw the YD-1¡s unique styling for the first time. This was later proved true by the fact that YD-1 owners became so enthralled with the YD-1 as a leisure-use sports machine that you almost never saw one mounted with a luggage rack, even though the rear fender had been reinforced to support one like most Japanese motorcycles at the time.