Cycle News - Archive Issues - 1970's

1""""4 M Q,) ..c 8 Q,) > o Z The man behind a lot of Vamahas By Brian George "I don't do anything that's not serious. It's a waste of my time," says Bill Stewart, 42, who in his 10 years with Yamaha Motor Corporation, has played a major role in many of the off-road 16 bikes that Yamaha has offered the public. Stewart has to I wasted has designed more pieces very little time. Bill of machinery for Yamaha than he ca n remember , and is the man who brought th e world the first IT Yamaha motorcycle , Taking a look back into Stewart's part. you will find a definite "natural ization" between himself and the sport of motorcyling . Bill really entered the world of motorcycles when he bought a retail motorcycle business in Redwood City , . CA , and took up observed trials riding and enduros. His first competition came in 1962, as a hillclimber. Starting out as a Novice, Bill won his first event , and moved into the Expert category in just five events , with a perfect record of five straight wins . It took only one full season before Bill was crowned California State Lightweight Division Hillclimb Champion in 1963 , on a 250cc mount . Observed trials was Stewart's next stepping stone. With most all of the hillclimbing season held during the summer months , Bill switched to winter trials events for a little fun on the rocks. Although Stewart says, " I never really got serious about observed trials ," he sold his dealership and set out to ride back East. After riding mostly the bigger trials events, Stewart went to Sedan, KS, and won the titl e of United St ates National Trials Champion . During the trials and hillclimbing , Bill also rod e enduros. This, too , started out as just something for pleasure to Stewart , but when he went to an Expert in one season. he was sent to East Germany in 1964 to compete on the ISDT team , with a factory CZ underneath him . A silver medal was 'wha t he earned , and a trip the following year to the Isle of Man . Stewart did not fare as well in '65 , suffering a DNF in the event which no Americans finished . Back at home on th e National Enduro trail , Bill won five National events over the years. and ended his career on a bike in 1969 . That was the ' year of Stewart's last National enduro ride . and he fin ished by winning it overall . Yamaha grabbed the motorcycle ace in 1968 , when they started him in the Technical Research Department. Hisjob involved him with investigating and developing almost every motorized part built by the factory . The racing division was under that department at the tim e . so Bill helped labor on the road race machines of Gary Nixon, Dick Mann , Ron Pierce and Keith Mashburn , with the help of his partner Ray Martinez. With this Bill moved on to both Racing and Testing Departments for Yamaha . For four years Bill was the head of Testing. coordinating all tests and keeping a sharp eye out for his test riders . Now Stewart is set in the Racing Department aga in, making sure all on-the -road mechanics are supplied with everything they need . Probably the most important project that Stewart was involved in was the building of the very first scaled down motorcycle . In 1969, Bill , with the help of Martinez , put together a % scaled -down m ock -up motorcycle called the Yamaha Mini -Enduro. This machine was to start a new conce pt which is now the world of minicycles. It took the duo one month to design the non -functional prototype and send it off to Japan for production. To get this mock-up , Stewart and Martinez took a motorcycle, chopped the frame down , cut up the forks and redesigned a gas tank . Needless to say it was an instant success. After his little minicycle, Stewart went on to build the first Yamaha trials bike , which later developed into the TY series. In 1972, Bill built a working prototype 175cc machine from a CT·1 frame with modified geometry , a seat cha nge and another gas tank . What it all built up to was a competitive motorcycle. The 175cc motorcycle was used, as Bill stated. "so the factories could enter trials bikes with minimal investment. " Some years later, the Yamaha people in Japan introduced their first production trials model . a 250cc machine. q The year 1972 was a productive orie for Stewart as he spent most of the summer on a dune buggy. The machine never went into production though, because "the project was shelved when land closures were started and the dollar went through devaluation, " he recalls. During this time , Bill had other projects going on the side. testing motocross , street, Baja and enduro works bikes. Then ne came up with the first high -outpiit Yamaha lighting system for the Baja . And this same system is still in use by top riders today . Things really began to happen in '74 . The TY series was beginning to roll out a year away from introduction . From a mini enduro , Bill designed and built the first TI80 trials bike. and played a big roll in tlie TT 500 thumper , introduced in- tlie '76 lineup. The original concepts of the TT500, all th e specifications, tHe weights. measurements and any other component they put into th e machine were products of Bill Stewart , He also did all of the prototype testing. Still the year was 1974, where Bill took a team of Americans over to Scotland to test the reliability of the ' trials mounts, Every Yamaha TY motorcycle entered finished. With Hie success of the TY under his lieli , Stewart developed the first serio :"s enduro motorcycle to come out of the Yamaha drawing room. It took three months to build a mock-up, but then it was all up to Japan to produce tlie IT enduro motorcycle. Not wanting to wait for test results from the factory, Stewart designed a working prototrne from a Yamaha TZ motocross machine , and to get a large enough gas tank , he took two YZ fuel tanks . cut them in two . welded them back together into one tank and had tlie tank design now used on the tflT motorcycles . Chris Carter was the man to throw a leg over the machine in competition; and he worked with Bill in a racing and development tvpe program . To test th e bike's reliability . . the machine was ridden in six qualifiers the first season , and the Isle of Man , and not one DNF was recorded . The second season saw tfie first produ ction models on the showroom floors . and the Yamaha Enduro Team rode the whole qualifier season and th e Austrian ISDT without a ' malfunction. In Austria , every rider of Team Yamaha finished , and with a gold medal to bootl The third qualifier season was another flawless time as not one machine suffered a DNF, and · it wasn 't until Czechoslovakia that one of the ma chines didn 't make it. Now Bill has more tim e to himself while at th e fa ctory , and his latest development was a monoshock trials bike. With all he has done for th e world of motorcycles, it ca n be said that " whe n America needs a better idea , Bill Stewart puts it on wheels ." •

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