The premier class of GP motorcycle racing, has changed dramatically in recent years. From the mid-1970s until 2002 the top class of GP racing allowed 500 cc with a maximum of 4 cylinders, regardless of whether the engine was a two-stroke or four-stroke. Consequently, all machines were two-strokes, due to the greater power output for a given engine capacity. Some two- and three-cylinder two-stroke 500s were seen, but though they had a minimum-weight advantage under the rules, typically attained higher corner speed and could qualify well, they lacked the power of the four-cylinder machines.MotoGp In 2002, rule changes were introduced to facilitate the phasing out of the two strokes, probably influenced by what was then seen as a lack of relevance: the last mass-produced 500 cc 2-stroke model had not been available to the public for some 15 years. The rules permitted manufacturers to choose between running two-strokes engines (500 cc or less) or four-strokes (990 cc or less). Manufacturers were also permitted to employ their choice of engine configuration. Despite the significantly increased costs involved in running the new four-stroke machinery, given their extra 490 cc capacity advantage, the four-strokes were soon able to dominate their two-stroke rivals. As a result, by 2003 no two-stroke machines remained in the MotoGP field. The 125 cc and 250 cc classes still consist exclusively of two-stroke machines. In 2007, the MotoGP class had its maximum engine displacement capacity reduced to 800 cc for a minimum of 5 years.