Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
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CN III ARCHIVES BY LARRY LAWRENCE I n 1981 an impressive group of racing and tuning talent banded together, with Yamaha factory back- ing, and built a Virago XV750-based flat track racing machine. The effort, inspired initially by the wishes of Yamaha dealerships across the country wanting to see Kenny Rob- erts back in AMA Grand National competition, was headed by racing legends Kenny Roberts and Mert Lawwill and backed by a vastly ex- perienced crew that included Dick Mann, Bud Askland, Mike Libby and C.R. Axtell. A hoped side benefit of the Yamaha XV dirt track project was making the engine available to privateer teams for under $2000, this at a time when it cost $5000 for an XR750 motor. Yamaha shipped in 75 motors for just that purpose, yet for all the promise the XV project held, it ultimately was abandoned after two years of development by some of the best in the business. In 1981 when the XV project came to fruition, Kenny Roberts was primarily still focused on win- ning the FIM 500cc Motorcycle Grand Prix Championship. That meant Lawwill was doing the bulk of the overall development work on the XV, Lawwill and Mann were working on a cradle frame and suspension, while Axtell was on the P116 cylinder ran considerably hotter than the front, requiring the rear cylinder to use a different cam than the front. The front camshaft drove the repo- sitioned ignition. Both cylinders had dedicated points and coil. Horsepower was rumored to be in the same ballpark as an XR750, which, at the time, was 80 horse- power give or take. Lawwill said the XV engine could conservatively go 100 race miles between rebuilds. One oddity with the XV was that the engine ran backwards, mean- ing the crank spun in the opposite direction of the wheels. Lawwill and crew initially dismissed the effect this would have on handling, but Kidd said he felt the backwards spinning caused caused the bike to stand up in the turns. "When you were sitting in the pits with the engine running on a Harley, dyno trying to coax a wide and strong power- band from the Yamaha V-Twin. Handling the riding chores on the pro- totype Yamaha XV750s were Yamaha factory- contracted riders, veteran Mike Kidd and up-and-coming rookie expert Jimmy Filice. The XV750 was Japan's version of the American XV920. In the U.S., the bikes were shaft driven, but in Japan, both shaft- and chain-driven versions were available. Modifications to the XV to make it ready for racing includ- ed an aluminum left side cover that helped narrow the engine width. That also meant moving the ignition and alternator. Since the XV's stock crank was overbuilt to handle the power of a 920 and even 980cc version (sold in Europe) the crankshaft and lower end were deemed strong enough for racing the 750cc version. The XV flat tracker used two 38mm Dell 'Orto carbs. One issue with the XV motor for racing was the rear cylinder exhaust exited the back of the head, meaning the pipe had to be bent and shoe-horned between the gearbox and swingarm. The routing blocked airflow and also meant the rear YAMAHA'S V-TWIN FLAT TRACKER Yamaha's attempted XS750 flat tracker.