Many believe vengeance drove Honda's decision to go dirt-tracking. Harley had won a trade judgment against Japanese bike-makers for "dumping" inventory in America, and the resulting tariffs dramatically increased import prices. Shortly thereafter, Honda stormed the only racing realm in which H-D excelled. They built a Japanese knock-off of the XR-750 V-Twin, but with overhead-cam four-valve heads (to this day, the Harley is a pushrod two-valver). Unleashed on the ultimate real-world dyno—the mile—the RS750 was a game-changer. Undefeated on mile tracks for eight straight years following Roberts' epic Indy win, the XRs managed only nine big-track victories in 39 tries from 1984–87, the reign of the Honda factory team starring Don "Bubba" Shobert, pint-sized powerhouse from Lubbock, Texas, and "Rocket Ricky" Graham, the incredibly talented head case from Salinas, California.