Home Street bikes 2-Stroke Yamaha YA-1 125 ccm 1955
Yamaha YA-1 125 ccm 1955

Here is Yamaha's first motorcycle, the YA-1, as it is proudly displayed in Yamaha Japan's "Communication Plaza".

Yamaha YA-1 (Feb. 1955)

Yamaha’s entry into the fiercely competitive Japanese motorcycle market was this sleek lightweight, modelled after the famous German DKW RT125. Measuring 1980 mm (78 in.) in overall length and powered by a 2-stroke single cylinder 123 cc 5,6 hp engine, the machine was fitted with a new 4-spped gearbox as compared with the original DKW’s 3-speed unit. Tire size was 2.75-19.

yamaha ya-1

The YA1 was usually light for a contemporary 125 cc motorcycle, scaling 95 kg (209 lb). The YB1 was a sister version enlarged to 127 cc, and could be distinguished by its colour scheme which was black with a chromed tank.

yamaha ya-1 125 cc

At the start of the development, President Genichi Kawakami gave a strict order to copy the RT125 completely. The reason was if the company could copy the world’s leading motorcycle, it would be able to make a debut that would eclipse its domestic rivals. In Reality, however, the engineers worked to develop new features through much trial and error in the developing process.

yamaha ya-1 125 cc

The first cylinders, developed based on the technique used to make piano frames, looked like lumps of steel and were jokingly called “teapots.” Besides, they lagged far behind the elegant shape of the DKW RT125 because they were made using sand mould castings.

yamaha ya-1 125 cc

Undeterred, the engineers continued their strenuous efforts despite repeated failures. Gradually they succeeded in achieving what was extremely precise casting for the time. Their efforts had borne fruits.

yamaha ya-1 125 cc

The engine itself was modelled on the RT125’s, but the transmission had four gears instead of three. Furthermore, it had a new structure in which the gear-change pedal and the kick-start pedal shared the same axis. The starting mechanism employed a primary method, in which the rider could start the engine no matter what position the gear was in as long as the clutch was disengaged. Revolutionary ease of operation was also adopted, it was possible to shift directly in neutral with just a half=stroke operation from any gear.

yamaha ya-1 125 cc

These technical features clearly distinguished the YA1 from the model upon which it was based.

There were other features, too. In the mid-1950’s, the priorities in motorcycle manufacturing were durability and utility. At Nippon Gakki however, the emphasis was on light weight and mobility in the design in every part. There was great originality in the shapes of the pedals for gears, kick-starter, and brakes, which were designed with artistic curves. These design characteristics made the motorcycle more than merely a copy of a European motorcycle. They were the results of the         quest for performance and the high targets set by the technical staff.

yamaha ya-1 125 cc

In those days, when most of the world’s motorcycles were black, the two-tone colour scheme of the YA1, which was painted reddish brown like the “chestnut coat of a fleet horse” and cream, was sensational. It gained the affectionate nickname of “Akatombo” (the Red Dragonfly), thanks to its engine, which would always start with a light kick, its sharp acceleration, and its free and easy handling. A group of students known as “GK”, (Group of Koike) led by Assistant Professor Koike of Tokyo National University of Fine Arts and Music, developed its colour scheme.

During this period, President Kawakami was always at the production workplace providing leadership. He even took part in test drives of prototype vehicles and assembling engines. He also participated in a durability test of 10.000 kilometres, which was unprecedented for motorcycles in those days, running on the public roads around Lake Hamana.
 

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