Im interested in understanding what drove the focus from the 500cc to the 250cc + when. . I know the quick easy answer is probably technology like lite frames + advanced suspension made the liter bike quicker than the more powerful bike. . But Im interested in understanding how it played out The FIM started the 500MxGPs in 57 but no 250MxGP until 62, so the focus then was the 500s. . Roger DeCoster won his championships in the 500 class from 71 to 76. . The 500cc Carlsbad GP was the "most-watched motorcycle race in the country on ABC's Wide World of Sports until 1986" and the movie "Carlsbad USGP: 1980 -- One Day of Magic" immortalizes Marty Moates win even tho Marty Tripes had already won the 250cc USGP in 1978. . So the focus then was still on the 500s. But at some point the focus changed. . 93 was the last year AMA raced 500s. . The FIM downgraded their 500 class to a MX3 budget support class in 2003 So somewhere between 1980 + 1993 the focus shifted from 500s to 250s. . By the time the 450 4strokes came in 97, the 250 class was already considered the top class What happened between 80 + 93 ? . What drove the focus to change ? . And was there a point or year when the top racers left the 500s for the 250s ? . Was there one specific technology development that drove the switch ?