In 1976 the AMA introduced a racing class for production based bikes and Yoshimura established himself by entering fast, reliable Kawasaki Z1 bikes. In 1978 he switched to Suzuki bikes and began winning races.
The American Medical Association launched a racing category for factory-produced motorcycles in 1976, where Yoshimura distinguished himself by riding fast and reliable Kawasaki Z1 machines. By 1978, he shifted to Suzuki models and began securing victories in competitions.