History
In 1971, Yamaha teased the world with a fourcylinder water-cooled two stroke job that set the tongues wagging at the Tokyo Show, but it was a charade. What eventually transpired was not a four, or even a three, but a twin - a 360-degree 2 valve twin at that. The TX750 arrived in Australia for its world debut in July 1972, accompanied by Yamaha’s Managing Director, Mr Hideto Eguchi. Actually 743 cc, the TX750 developed 63 bhp and Yamaha said it would be the forerunner of a whole new range of similar twins. Inside the engine was what Yamaha called an Omni-Phase balancer - a pair of weights with one designed to counter the primary imbalances created by the firing strokes, and the other to counter the rocking-couple that was created by the first balancer. This, Yamaha claimed, produced a twin with the inherent smoothness of a four, and by and large, the journalist who tested the early models agreed. The engine had been designed with the looming threat of anti-pollution legislation in mind. Sintered alloy valve seats were used, and the crankcases ventilated by a system where gases were fed into the air box via a reed valve to be recirculated. The TX750 certainly handled considerably better than the other big twin in the range, the XS1/XS2 which had been renamed the TX650, and finish was regarded as excellent. The five-speed gearbox actually came from the 650.
Chassis wise, the TX750 didn’t break any new ground, but there were nice touches such as the valanced alloy rims, which were there primarily in the interests of weight saving - at 210 kg the TX750 was a bit on the hefty side. The single overhead camshaft engine looked superb, all chunky polished aluminium alloy with a neat finned exhaust manifold that doubled as a balance tube between the two header pipes and further smoothed out the pulses from the counter-balanced twin cylinder engine. Although only a single front disc was fitted, there was provision for a second, with the mounts already on the left fork leg. European models received twin discs as standard. In Australia, buyers had a choice of dark green metallic with gold trim, or an all-gold decor.
Instrumentation was quite extensive, for the time, with a cluster of lights to indicate oil pressure (or lack of it), a brake light warning in case the bulb blew, either the tail or stop filament, or both, and a light to indicate when the rear brake linings dropped below 2 mm. The speedo and tacho were big and easily read, the latter incorporating a high beam indicator and neutral light.
