Rizla Suzuki Girls, Chinese MotoGP 2007

• MotoGP class
New specifications for each racing class are formed as the FIM sees fit. At the beginning of the new MotoGP era in 2002, 500cc two-stroke or 990cc four-stroke bikes were specified to race. The enormous power advantage of the larger displacement four-stroke engine over the two-stroke eliminated all two-strokes from competition; the following season no two-stroke bikes were racing. In 2007 the maximum engine capacity was reduced to 800cc without reducing the existing weight restrictions.
MotoGP-class motorcycles are not restricted to any specific engine configuration. However, the number of cylinders employed in the engine determines the motorcycle's permitted minimum weight; the weight of the extra cylinders acts as a form of handicap. This is necessary because, for a given capacity, an engine with more cylinders is capable of producing more power. If comparable bore to stroke ratios are employed, an engine with more cylinders will have a greater piston area and a shorter stroke. The increased piston area permits an increase in the total valve area, allowing more air and fuel to be drawn into the engine, and the shorter stroke permits higher revs at the same piston speed, allowing the engine to pump still more air and fuel with the potential to produce more power, but with more fuel consumption too. In 2004 motorcycles were entered with three-, four-and five-cylinder configurations. A six-cylinder engine was proposed by Blata, but it did not reach the MotoGP grids. Presently four cylinder engines appear to offer the best compromise between weight, power, and fuel consumption as all competitors in the 2009 series use this solution in either 'V' or in-line configuration.
In 2002, the FIM became concerned at the advances in design and engineering that resulted in higher speeds around the race track. For purposes of increasing safety, regulation changes related to weight, amount of available fuel and engine capacity were introduced. The amended rules reduced engine capacity to 800cc from 990cc and restricted the amount of available fuel for race distance from 26 litres in year 2004 to 21 litres in year 2007 and onwards. In addition, the minimum weight of 4 cylinder bike used by all participating teams was increased by 3 kg.