Yamaha DT / TY / XT Brochure

Here's a higher res image of the TY page from the brochure below.

And this is the text from the image:

Yamaha TY Series. . . With the Balance and Performance to Win Every Trials Event

Yamaha’s great new Trials models, the TY125 and TY250, are the result of Yamaha’s engineering skills as well as all of the experience and knowledge of one of the world’s top Trials riders, Mick Andrews. Every engineering feature and styling point has won his critical approval after severe tests. Lightweight and highly manoeuvrable, and with exceptional balance capabilities, these machines will meet and exceed the requirements of even the most demanding Trials rider. Yamaha has with these machines once again taken the leadership in motorcycling technology, combined it with unexcelled experience, and shown the way to the champion’s circle.

Engine

The Yamaha Trials series models are powered by engines especially developed for this gruelling test of man and his machine. Single- cylinder, 2-stroke design - a technology where Yamaha excels with scientifically determined piston design painstakingly matched to induction and exhaust ports. Low-speed power and instant response are superb to meet the demands of even the toughest sections. And, of course, Yamaha’s exclusive Autolube lubrication system assures a precisely measured quantity of clean oil from a separate tank thus assuring the maximum efficiency of the charge of fuel drawn in for every firing stroke. Add to this the proven worth of Yamaha’s Reed-Valve Torque Induction system, and you have the best possible Trials engine, with the finest possible performance.

Speedometer

Street-legal speedometer has been especially mounted in a well-protected position behind the left fork strut.

Transmission

The widely spaced gear ratios (5 for the TY250 and 6 for the TY125) have been carefully engineered to assure perfect performance at any speed—not only in competition in the sections themselves, but also for road and trails between sections. A feature worthy of special attention, moreover, is the gear change pedal which folds back when hit by rock or tree stump, assuring the rider that the machine will never be knocked out of gear.