Yamaha was also facing the industrial conversion of factory machine tools that had been used during the war for the production of fuel tanks, wing parts, and propellers for aircraft of the Imperial Japanese Navy, such as the Mitsubishi A6M Zero fighter.

[6][7] As in European countries, the motorcycle had become a widespread means of transportation in Japan after World War II due to ease of production and economy of purchase and use.

In January 1955, Nippon Gakki's (Japan Instrument) Hamana Factory in Hamakita was ready to begin production of the YA-1, and the first bikes were delivered to dealers in February.

Outstanding race performance had made the YA-1 much more desirable, in spite of its price of ¥138,000 in 1955 (for comparison, a male college graduate's starting salary was ¥10,780 on average).

[1] Previously, motorcycles with a non-primary starting system used the transmission input shaft and clutch hub to connect the kick-start lever to crankshaft.

[15][16] The modified engine is based on the power plant of the YBR125 and Yamaha claims a fuel consumption of 80 km/L (230 mpg‑imp; 190 mpg‑US) for the Y125 Moegi, making it efficient personal transportation in urban environments.