Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/125691
'"o S :. o .... - Cll a "l~-------------;:----------------::-:;--::---------";;------"'-"---"~""""""7""-,,:l~~!!!!!1 ~ w Z W ..J U > U More than three years of preparation went into the record run. By Bruce Flanders BONNEVILLE, UTAH, Sept. 17, 1970 - Don Vesco today became the fastest motorcycle rider in the world, as the soft spoken and methodical racer from El Cajon, Calif. blasted his twin, gas powered, 350cc Yamaha streamliner down the salt flats at an incredible two·way average of 251.924, adding more than six miles an hour to the four year old record of Robert Leppan. Vesco had spent more than three years perfecting his big machine to the point where it has now officially eclipsed the existing A.M.A. mark set by Leppan in 1966 at 245.667 MPH. Leppan's mark was established with two 650cc Triumph (1300cc total) on fuel, while Vesco's record was on certified pump gasoline. It boggles the mind to think of the potential this machine would have on some exotic blend of hero juice. But Don isn't that sure about the use of fuel. "Whenever I go roadracing I'm accused of using fuel". "Actually, I get all the horsepower needed on gasoline and haven~t even started playing with fuel." The fact that he can go 251 MPH on gasoline bears this out. And as if it weren't enough to have already put Vesco and crew make some last minute adjustments. away the ultimate land speed record for motorcycles, the next day Vesco disconnected the interconnecting chain between engines and proceeded to pop the 350cc records out of sight. He pumped the 350 fuel streamliner record to 193.756 MPH, then turned around and shot the gas record to 197.813 for the two way average. It should be pointed out here that he did not remove the other engine and was pulling the dead weight of the other motor. He later said that next year he would like to put the 350 record over two bills, and we don't doubt he'll do it for a minute. UB'ig Red", which is Norma Vesco's nickname for the streamliner (no relation to the nationally franchised cesspool pumping outfit) still had the scars from sliding through the traps at 252 MPH during Bonneville Speed Week. A tire failure, after an obvious strong run was the cause of this magnificent unload. It was determined by the Vesco crew that it must have been a slight imbalance in the tire which crea.ted a harmonic at top speed, thus terribly overloading the tires on their sanitary scooter. Tires are always a problem at Bonneville, no matter how fast you go. But once the 200 barrier is passed, the tire problem increases geometrically in ",roportion to the speed. Dunlop tire (England) was the most receptive to Vesco's worldwide cry for help to tire manufacturers, providing more than enough tires for his successful assault of the record. Vesco said he is also indebted to Custom Machine for the mag wheels, which,' he pointed out, add immeasurably to the stability of his rig at high speed. These wheels, he not-too-subtly added "can be ordered through my shop in E1 Cajon." One of the happiest crewmembers on the salt was Bob Westbrook from Santee, Calif. You may remember him from the abstract picture of a c.ompetition BSA during our speedweek coverage. Bob was the right hand man who helped from the early days of construction on UBig Red". He can now also lay claim to having produced ,the world's fastest expansion chambers. This is a sideline with him and may soon be a full time business, especially when people find out about his reputattion for specailty applications. For'those of you that dig details, the engines are "practically stock", 348cc Yarnaha roadracing engines. The coupling is by chain in the normal drag bike tradition. The transmission is retained in the rear case with nearly normal, 5-speed roadracing ratios, with the front trans "sawed off". The skin started life as a belly tank from a USN F9 F jet aircraft, with aluminum modifications. The parachute is by Diest of drag chute fame, with very neat steeing being provided through a center kingpin device. The horsepower produced by the double is apparently a secret..because all Don will do is scratch his chin and