2004/2005
Valentino Rossi signed a two-year contract with Yamaha, reportedly worth in excess of US$6 million per season, in a move that was described by the press as "biting off more than he could chew". It was widely felt not only by his critics and media pundits, but also by many fans, that even he would not be able to bring the struggling YZR-M1 up to the level of the hereto all conquering Honda RC211V. A well publicised increase in the pace of development of the Honda machine over the winter season fuelled expectation that a Honda RC211V the hands of riders the calibre of Max Biaggi and Sete Gibernau would have no problem in retaining the World Title for Honda.
Meanwhile, Rossi wasn't the only defection Honda had to contend with; Jeremy Burgess (crew chief for Rossi at Honda), along with the majority of his long established crew, were convinced by Rossi to join him at Yamaha. This was a shrewd move, and was cited by Rossi in his autobiography as being instrumental in providing him with the strong basis necessary for launching an attack on the Championship with the YZR-M1.
During 2003/2004 winter testing, Yamaha stepped up to the plate by pulling out all the stops in their collaboration with Rossi and Burgess. Through a systematic regime of innovation and testing, they sought to refine the M1's traditionally strong traits such as good braking and quick handling (which impressed Rossi), and marry them with good balance and transition to power. Working closely with Rossi and Burgess, Yamaha engineers under YZR-M1 project leader Koichi Tsuji experimented with a number of engine modifications in an attempt to fix the power delivery, and finally it was decided to go ahead with a four valve per cylinder head configuration (as opposed to the earlier five valve head), with a specially refined cylinder firing order. This turned the straight four cylinder engine from a traditional "screamer", where the power pulses are spaced equally (every 180 crank degrees) in the four stroke cycle, into a so called'''long bang'' engine where the power pulses are grouped unevenly across the cycle (270-180-90-180). This firing order mimics that of a V4 engine while maintaining the desirable engine packaging of a traditional inline four cylinder. These developments significantly improved the torque characteristics of the engine, and coupled with slight changes to the position of the engine in the chassis, made the M1 much easier to control at the limit of adhesion while exiting corners. After a frantic winter of development and testing, the team showed the world that they had made a significant step in the right direction, when Rossi and the M1 won the BMW car at the 2004 pre season IRTA test at Catalunya, by posting the fastest lap of the open session (similar to normal race qualifying).
With the traditional first race of the season at Suzuka off the list due to safety considerations, the 2004 season started at Welkom in south Africa. In a quite remarkable race, Rossi came through to claim the victory, not only silencing his critics, but becoming the first man in history to win two GPs back to back with two different manufacturers. Rossi would go on to claim 8 more GP wins on his way to win the 2004 Championship, with a tally of 304 points. Honda riders Sete Gibernau and Max Biaggi took second and third with 257 and 217 points respectively.
The 2004 season would therefore unfold to give Rossi the opportunity he had sought; to prove that it was his talent rather than just the bike that had won him his championships. In so doing, he also achieved one of the great coups in the history of Motorcycle Racing.
The YZR-M1 and Rossi partnership continued to dominate in 2005, when the Championship was won by a massive 147 point margin over Honda rider Marco Milandri in second place.The 2005 M1 was hailed by insiders to be a great race bike, it illustrated that Yamaha with input from Rossi had created a race bike to beat the others quite easily. Rossi would go on later to say that the 2005 M1 was the greatest bike he has ever ridden.
Aantal onderdelen; 50.
Afmeting: 229 mm.
