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Yamaha YD1 250

Make Model	Yamaha YD-1
Year	1957
Engine	Two stroke, piston-port, parallel twin
Capacity	247 cc / 15.0 cu-in
Bore x Stroke	54 x 54 mm
Cooling System	Air-cooled
Compression Ratio
Induction	Single carburetor
Starting	Kick
Max Power	14.5 hp @ 6000 rpm
Max Torque	4.1 kg-m @ 5000 rpm
Transmission	5 Speed
Final Drive	Chain
Front Suspension	Telescopic forks
Rear Suspension	Swing arm
Front Brakes	Drum
Rear Brakes	Drum
Front Tyre	2.50 -16
Rear Tyre	2.50 -16
Wet Weight	138 kg / 309 lbs
Fuel Capacity

Yamaha, the youngest of the "Big Four" Japanese motorcycle manufacturers, didn't build its first two wheeler until 1954, when it unveiled a copy of the DkW RT 125, calling it the YA1. this spidery autocycle was a great success. It won handily the first cinder track hillclimb ever held at Mount Asama, north of Tokyo, in both 125 and 250cc classes. It was a decisive moment for Yamaha.

Inspired by Adler

But Yamaha's competitors were not standing still, so in 1957 Yamaha launched a new 250cc model, this time based on the Adler MB 250. The new bikes main difference was in its frame, which was a pressed steel copy of the German Adler's cradle frame. Maybe that wasn't such a good idea! The first racing versions of the 250 YD1, seen at Mount Asama in 1957 and in the Catalina United States Grand Prix in 1958, went back to the original German cradle design!

A Brilliant Dynasty

Yamaha was a fast learner and, within a few years, its twin had cast off all traces of its origins and had given rise to a motorcycle dynasty. The first was the electric start YD2. then came the first dedicated sports models, the YDS1 and the YDS2 (the first model exported to Europe). Yamaha competed in its first French GP at Clermont-Ferrand in 1961 and returned in 1963 with a succession of famous riders - Vesco, Read, Redman, Ivy, Saarinen, and Agostini.