In 1984, he accepted an offer to ride for the newly formed Kenny Roberts Yamaha racing team in the 250cc class of the Grand Prix World Championship. A less than successful season (1 podium and difficulty push-starting the bike) saw him returning home in 1985 to join the Maclean Racing team in U.S. 250 and Formula 1 classes, and then on to the American Honda team from 1986 to 1987 where he raced Superbike and F1. It was during the 1987 Superbike National Championship that his intense rivalry began with Kevin Schwantz as the two battled it out for the title. Rainey won the Championship, but the fierce rivalry between the two competitors was just beginning. So intense was their rivalry that they continued their battle during the 1987 Trans-Atlantic Match Races in which they were supposedly teammates competing against a team of British riders.