YAMAHA

250 YDS 3-1964

Building on the first twin

It all began in 1957 with the YD 1, Yamaha's first 250 twin which, as it was steadily

developed, allowed the Hamamatsu company - which had started in 1887 as a maker of reed-organs - to dominate the market for medium-displacement sports twostrokes.

Two Big Selling Points

In 1964, Yamaha launched a new version of their successful 250, the DS 3, which came on the scene with two unique selling points: firstly, that very year Phil Read had won Yamaha's first 250cc world championship riding a twin-cylinder bike closely related to the production model, while the new Autolube lubrication system eliminated the tiresome need for two-stroke riders to mix oil with their gasoline.

The Autolube

The Autolube was a mechanical pump whose output varied with the throttle opening. It was a fairly basic system that just ensured that the oil was injected in the light proportions without - as Suzuki would do later - ensuring that oil was fed under pressure to critical points. The engine of the DS 3, still with a horizontally divided crankcase like its distant ancestor the Adler, was a distinct improvement on the DS 2, launched in 1962, gaining a third crankshaft main bearing. On its introduction in 1964 it developed 24 hp @7500 rpm, and by the final version in 1967, power output had risen to 28 hp@ 8000 rpm. As for its performance, it was outstanding for its clay. The claimed maximum speed was 90 mph in 1964 and over 96 mph in 1967.

SPECIFICATIONS

Engine: 246cc (56x 50mm) air-cooled twincylinder

Power Rating: 24 hp @ 7500 rpm

Valves: two-stroke

Fuel System: two carburetors

Transmission: 5-speed; chain final drive

Suspension: telescopic fork (front); swinging fork with two spring/dampers (rear)

Brakes: twin leading shoe dmm (front); drum (rear)

Wheels: 18 inch

Weight: 350 lb

Maximum Speed: 90 mph

Typical of its day, the dial in the headlamp shell incorporales speedometer and tachometer.