By the late 1960s Japanese motorcycle companies began challenging the European factories for supremacy in the motocross world. Suzuki the first world championship for a Japanese factory when Joël Robert won the 1970 250 cc crown.The first stadium motocross event took place in 1972 at the Los Angeles Coliseum. In 1975 a 125 cc world championship was introduced. European riders continued to dominate motocross throughout the 1970s but, by the 1980s, American riders had caught up and began winning international competitions.
During the late 1970s and early 1980s, Japanese motorcycle manufacturers presided over a boom period in motocross technology. The typical two-stroke air-cooled, twin-shock rear suspension machines gave way to machines that were water-cooled and fitted with single-shock absorber rear suspension. In the 1990s, America’s leading motorcycle sport governing body, the AMA, increased the allowable displacement limit for four stroke powered machines in the AMA motocross championship, due to the low relative power output of a four stroke engine, compared to the then-dominating two stroke design. By 1994, the displacement limit of a four stroke power motocross bike was up to 550 cc in the 250 class, to incentivize manufactures to further develop the design for use in motocross. By 2004 all the major manufacturers had competing with four-stroke machines. European firms also experienced a resurgence with Husqvarna, Husaberg, and KTM winning world championships with four-stroke machinery.