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GP Week : Issue 208
MOTOGP >>> FEATUrE Nothing stays the same in World Championship motorcycle racing – but on occasion, history can repeat itself. Take the lot of some of the riders in each MotoGP. The likes of Nicky Hayden, Scott Redding, Hiroshi Aoyama and Karel Abraham go to the line for every race in the full knowledge that their Hondas lack some of the go-fast technology of the similar, but different, bikes of Marc Marquez, Dani Pedrosa, Alvaro Bautista and Stefan Bradl. There are no pneumatic valves for those on Honda’s RCV1000R. No power shifter either. In an event not interrupted by weather, earthquake or other unexpected occurrence, the €1m-plus racer does not stand a chance of getting onto a podium, let alone winning a MotoGP. Such has been the way in motorcycle racing for a long time. Race ready bikes have been available for years – think 1947 and Manx Norton – but never has so much performance been put in the hands of so many racers as happened in the 1970s. In 1973, Formula 750 was a coming category. Largely production-based engines found their way into a number of specialised chassis, and the result was a number of four-stoke motors taking on some two-strokes – notably from Suzuki and Kawasaki – in a high speed fight for supremacy. The machines may have been unsophisticated compared to the 500cc GP racers of the day, but on the right track, they were just as fast. But there did not always race on the ‘right’ track. In 1972, Don Emde followed in the wheeltracks of his father Floyd and won the Daytona 200. Emde Jr won on a Yamaha – but it was a 350. The bigger, heavier triples were faster but their tyres would not go the distance. The Yamaha TR-3 was a good bike. So, twice the bike would be twice as good, surely? The logic was simple; it was only a matter of time before the big bikes were going to get faster, too fast for the smaller machines. Problem was, while many of the other makes had suitable hardware to consider modifying into F750s, Yamaha did not have a suitable big-engined bike. The FIM and AMA’s homologation rules required 200 examples to be built to make bikes eligible for F750. No manufacturer would make 200 race bikes, surely... The bike was called a TZ750 (Yamaha’s in-house codename was YZ648). Yamaha engineers took the two sets of cylinders (64mm/bore and 54mm/stroke) from the TZ350 that had been developed for GP racing, detuned the power and mated them on a single crankcase. The result was a 694.9cc in-line four with a bit more than 90 horsepower, in a bike that weighed about 155kg. It was staggeringly fast – almost too fast for any tyre (and many riders) of the day. Yamaha had engaged the recently- retired former World Champion Kel Carruthers to develop its racers, and he flew to Japan for his first acquaintance of the bike terrified him. It was almost uncontrollable. After a few hair-raising laps, he pitted and handed over to one of Yamaha’s in-house test riders – who lasted no more than three laps before he came in and simply refused to ride the bike again. Carruthers suggested that the racer was too short in the wheelbase and the prototype’s swing arm was hastily lengthened by 75mm. The result was a much more usable machine, so the bike was sent to the USA for Yamaha’s new signing, Kenny Roberts, to try. He took to the bike at once; it was scary, but manageable. Not for many other riders. The front forks were 24.5mm wide – you would not see forks that slender on anything faster than a 250 roadbike today. But the bike ABOVe Note the difference between the TZ750s privateers could buy (right) in 1978 and the factory racer Johnny Cecotto rode that same year (left). The factory bike features a quick-fill fuel tank, bigger forks and brakes, a thicker but lighter alloy swing arm and mag wheels. The bodywork is different, and customised versions of the hand-made pipes were available, depending on the circuit. Images: Yamaha Racing PReVIOus PAGe Who was the first American to win a World road racing title? Most people will say Kenny Roberts but Steve Baker, from Bellingham, Washington, took out the World 750 title in 1977 on his Yamaha Canada TZ, a year before King Kenny won his first 500cc title. 25 GPWEEK.com // 25 GPWEEK.com // PARTNERS: