Tweaking the TZ: Making the best even better
The mid-1970s brought a period of consolidation for Yamaha. The firm was now 20 years old and well on the way to upsetting the perceived order of things; they also had Honda well and truly within their sights. With the 500cc title finally in their hands, Yamaha announced their official withdrawal from GP racing – although there would be some not so covert support for what were euphemistically termed satellite teams.
Arguably in a somewhat cynical move, the commercially available 1977 TZ750Cs rolled out for sale in the 1976 season were nothing more than 1975 B models. Of course, those bikes going to selected riders were nothing like the privateer machines. A further developed 750 motor was now housed in a subtly tweaked 500 GP chassis with lots of mass removed. The steering head became high strength aluminium with magnesium used for the yokes and titanium brake caliper pistons; the same metal was even used on the fairing mounts. Some 18 kilos had been shed and even the rear shock absorber had lost a couple. The chosen few –Agostini, Baker, Cecotto, Kanaya and Roberts – now had machines that would exceed 180mph.
At Daytona things didn’t go as planned. Tyre technology was still struggling to catch up with performance and Japanese rider Hideo Kanaya found his rear was totally gone at two-thirds race distance and King Kenny had similar issues towards the end of the race when the rear punctured, forcing him into the pits for new rubber and then finishing ninth. Canadian Steve Baker went out early, leaving Venezuelan Johnny Cecotto to win. These quasifactory machines – entitled OW31 – despite all their new tech and light weight, battled all year against machines that, on paper, they should have trounced. Erv Kanemoto and Gary Nixon had acquired ex-factory Kawasakis and collectively ran the Yamahas down to the wire.
Ironically, neither the OWs nor the KRs took the title; Spaniard Victor Palomo grabbed that on a privateer TZ750 and took the honour.
That F750 championship remained key to Yamaha’s commercial success in the showrooms and more time, effort and money were thrown into the TZ750D, which was essentially an OW31 minus the weight loss programme. Revisions to suspension, chassis bracing and exhausts saw the 1977 models offered the privateers for some $5200 or £6500. Serious money indeed and most of the buyers would soon be complaining vociferously. Yamaha’s race-building department had taken its eye off the ball big time! Mismatched pistons and cylinder, breaking foot pegs and steering dampers, plus other niggles, shouldn’t have been present at that price.
Things weren’t exactly rosy at Daytona either. Johnny Cecotto’s and Steve Baker’s machines had factory fitted Mikuni carbs complete with the new Power Jet System, but Kenny Roberts was now openly looking to improve on the factory offerings via the American produced Lectron carbs he and Kel Carruthers had been experimenting with the year before. Rain at Daytona turned the 200-mile event into a 100 miler with Cecotto’s mount sidelined with oil leaks. Baker took a near half-a-minute lead and Roberts seemed to be down on power, despite the fancy carburettors.
Aside from the headline-grabbing results, it was now becoming apparent that both riders and tuners were developing what was now referred to as ‘The Beast’ well beyond Yamaha’s own input. American firm, C&J, offered a bespoke chassis that mirrored the set up used by the parent company, yet was substantially lighter. Brighter minds were also looking at the way the engine breathed. Revised header pipes, slower flowing transfer ports and subtle smoothing of the air/ fuel’s movement all helped to make the 750 that little bit more rideable and competitive.
Even though times were changing and four strokes looked to be the future, the big Tee-Zee still had a few more years and a whole hatful of races left in it.
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