Daytona Dilemma: Roberts Vs Sheene

Roberts and Sheene first raced against each other at Daytona in 1974 – and over the next decade they went head-to-head more than 100 times. VJMC’s Steve Cooper looks back…

Despite eventually winning the 1982 Daytona event for the 11th time, the triumph was bittersweet for Yamaha. Kenny Roberts supposedly was the favourite on the OW60 that had some 156bhp on hand but the bike failed during the race. Graeme Crosby brought the bacon home for Yamaha but on a TZ750 – a machine Yamaha had officially stopped building, selling and running back in 1979!

The result should have been cause for celebration but, in reality, it just underlined the fact that the TZ500/YZR500/square four, half-litre, OW60 was failing to deliver. Not only were its shortcomings apparent at the crucial GPs across Europe, but also the bike had bombed out at Daytona which was a key sales tool in the crucial America market – action was needed ASAP.

It might seem like a knee-jerk reaction to just one race result but the importance of winning the Daytona race can’t be over-emphasised. Taking first place in Florida had a direct, tangible, effect on USA sales for the forthcoming year. Pushing the square four concept to the absolute limit, Yamaha’s boffins deliver the OW69. If the old, in-line TZ750 had been The Beast, then the new bike was The Monster. Taking the bore out to 64 millimetres with the retained 54 millimetre stroke gave 695cc of brutal power. The undertaking demanded revisions and strengthening of heads, cylinders, crankcases, crank, pistons and exhausts. Although ‘only’ drawn up to deliver 150bhp, the new motor was able to deliver the vital low and mid-range power the 500 OW60 was lacking. For the purposes of verification the race team also built a fully-tuned OW69 motor which was capable of producing some 175 horses. Perversely and despite all the issues with the donor chassis, the OW69 ran the OW60’s in virtually unaltered format!

In the run-up to the 83 Daytona the OW69 had been shaken down at Laguna Seca where, it transpired, the bike only did one thing well… go fast. KR’s language simply could not be reiterated in polite company but the jist of it was that the OW60 was a pussycat in comparison. At Daytona, Roberts was positively incandescent when the bike wouldn’t turn in as it was expected to AND was found to be pushing the front end at the same time. Heated exchanges with his mechanics and the Dunlop tyre people finally uncovered the problem. The front tyre was found to be some 50% down on pressure post-testing despite being correct initially. It was discovered the Dunlop boys had been pushing their tyre temperature probes into the rubber too deeply, effectively creating micro-punctures. Red faces and smug grins as appropriate, the issues were addressed, etc.

Roberts was followed home by teammate Eddie Lawson on a Yamaha first and second double, thereby restoring family honour. A year later Roberts ended up fighting with Freddie Spencer mounted on the Honda NSR500. Teammate Lawson was plagued with tyre wear problems. Roberts won from Spencer and announced he wouldn’t race at Daytona again. The 50mph disparity between the fastest and slowest was creating massive safety concerns for the top riders.

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