Yamaha TZ350 History

The incredible Yamaha TZ350, a brief history.

1973 saw the introduction of the bike which was about to transform the 350cc GP class worldwide, the incredible TZ350A. The inclusion of water-cooling in addition to other slight improvements over the bike's air cooled predecessors, the TR2, TR2B and TR3, saw Yamaha's 350cc production offering fast becoming an almost unbeatable weapon in the hands of the right rider. Internally the motor hadn't changed much from the previous model apart from the widths and angles of the transfers being altered to improve scavenging, though actual port timing remained as it was with the older model. Also the silicon content of the cylinder was lower compared to that of the TR3's separate hypereutectic units. The new bike produced a very respectable 60bhp @9,500rpm.

Interestingly, there was no variable advance built into the Hitachi TIA02-01 CDI controller used on the 350. Whatever ignition advance the tuner set was the advance right through the rev range. ( This was not the case with the TZ 250 ).

In 1974, the "B" model was released, with very few changes to the previous "A". As if this wasn't frustrating enough, TZ racers had to sit out 1975, waiting until the next year for a new version. The wait was worth it....

The "C" model, of 1976 was another matter entirely. Here was a radical departure chassis and running gear wise from the earlier TZ's. Adjustable "mono-shock" (spring preload and rebound damping only) rear suspension, combined with twin piston front and rear disk brakes set the world on fire, with the new bikes selling like hot-cakes from Yamaha dealers worldwide. The retail price of around £ 1,550 including a comprehensive spares kit was incredible value for money and did no harm at all to sales. The clutch basket "boss" was improved by changing it's method of attachment to a male / female spline system from the previous model's "dog" type. The exhaust header picked up an additional o-ring and a new mounting system. Power jumped up slightly to 62bhp @ 10,000rpm.

The "D" and "E" models of the next two years were a little disappointing from the "punter's" point of view due to the fact that very little was altered at the factory from the "C". Most striking difference were the exhausts, with fully integrated silencers.