The Grand Prix Commission - composed of Carmelo Ezpeleta (Dorna), Claude Danis (FIM), Sito Pons (IRTA) and Takanao Tsubouchi (MSMA) - has today confirmed that MotoGP engine capacity will be reduced from 990cc to 800cc for the 2007 season onwards.
The much rumoured move has been prompted by the need to reduce speeds - indeed; so far at this weekend's Italian Grand Prix all but 4 of the 21 MotoGP machines have broken the 200mph barrier, with Carlos Checa's Ducati hitting almost 210mph along the Mugello main straight.
The new capacity limit replaces a less radical rule announced last June, which declared that MotoGP engines would be reduced to 900cc for 2007.
Unlike the 900cc rule, the 800cc capacity is likely to force a substantial redesign of GP machines, with new cylinder configurations likely (HRC are already thought to have a three-cylinder under development).
It is also expected to result in machines with more 'peaky' power-curve characteristics as the emphasis moves from 'rider-friendly' to 'maximum revs' as engineers seek to replace the power lost.
The 800cc limit will run for a minimum of five-years, assuring manufacturers of stability in return for the new engineering investment needed. Fuel capacity for the 800cc machines will be limited to 21 litres.
Meanwhile, two-stroke MotoGP engines - of which there are currently none - will be officially consigned to history with the additional news that from 2007 they will not be allowed in the premier-class.
This decision was necessary to ensure the four-stroke future of the class, since a 500cc two-stroke (as presently allowed) could potentially be competitive against an 800cc four-stroke, possibly promoting something of a two-stroke revival - which neither the major manufacturers or sport in general wants.