Let's all so set the record straight for the last time I hope..it is OW-72..not OU, When I went out to buy Shells business he had 2 stilling in the shop. I asked what he wanted for them and he said $7000.00, I wish now I had them. Thanks Gary
A little history
Sold on Bill of Sale
- Shell 750 cc Yamaha Racing engine
- One of about 30 Factory OW 72 Yamaha Racing engines built
- Shell Thuet chassis and swing arm
- Built by Shell for Factory Yamaha effort
- Kenny Roberts flat track racer
- Later ridden by Hank Scott and Wayne Rainey
- All components period correct and in as raced condition
- Sold on Bill of Sale
- Shell 750 cc Yamaha Racing engine
- Flatslide carburetors
- One of about 30 Factory OW 72 Yamaha Racing engines built
- Shell Thuet chassis and swing arm
- Built by Shell for Factory Yamaha effort
- Kenny Roberts flat track racer
- Later ridden by Hank Scott and Wayne Rainey
- Shell pipes
- All components period correct and in as raced condition
- Engine # 447-711664
In the 1970s, the AMA National Championship motorcycle races were among the most keenly watched sporting events in the U.S., thanks to movies like “On Any Sunday” and television coverage of the racing season. As such, racing was an excellent advertisement for the factories, who were willing to invest tidy sums in engine and chassis development, as paychecks for star racers. The biggest star in ’76 was ‘King’ Kenny Roberts, who held the No. 1 plate for two years prior and was eager to retain his crown again. Roberts rode for Yamaha whose street-based XS650 engine was the basis for the company’s flat track racer, competing against the pure competition Harley-Davidson XR750. As H-D squeezed more HP from its V-twin, Yamaha tuners like Shell Thuet bumped against design limitations of the production XS650 cylinder head, halting at around 70 HP, and Kenny Roberts was not amused. Roberts had Shell Thuet fired as Yamaha’s tuner, and brought Tim Witham, owner of S&W Engineering, out of race retirement in hopes he could extract more power. Witham addressed the cylinder head issue directly, by designing a totally new head, which he estimated should make 90 HP, 5 more than the XR750. Yahama cast 25 of the entirely new heads for homologation as a new model. The factory sent machined but bare castings to California in batches, and Kel Carruthers built up running engines as required by the AMA, and even installed a racing engine in a fully road-legal machine. The new model was dubbed the OW72, and did indeed produce far more power than the street-based XS650 was capable of. The 750cc OW72 was serious competition for the mighty H-D XR750, winning plenty of races under Kenny Roberts, Hank Scott, and Wayne Rainey. This 1976 OW72 was Kenny Roberts’ racer, built by Kel Carruthers with the Witham cylinder head. It was later raced by Hank Scott, and Wayne Rainey, and features flat slide carbs, a Shell Thuet racing chassis, swingarm, and pipes. This OW72 is effectively a factory Yamaha dirt-track racer, built specifically for Kenny Roberts to retain his No. 1 plate. All components are period correct and in as-raced condition, and the engine number is 447-711664. Kenny Roberts declared this OW72, “the best thing I ever rode.”