Part one of the Yamaha technical presentation detailed how the YZR-M1 has evolved since its 2002 racing debut, and part two will now concentrate specifically on the 2006 machine.
Despite the 2005 YZR-M1 having taken a perfect sweep of the riders', constructors' and teams' world championships, the 2006 machine initially struggled with chatter, before a storming fight back during the second half of the season put reigning champion Valentino Rossi in the title lead for the Valencia season finale...
"As you know, we had a great season in 2005. So our development target for 2006 [see middle picture, click to enlarge] was to keep the same concept as 2005 but to improve the chassis agility a bit more and increase braking stability," revealed YZR-M1 project leader Koichi Tsuji, before commenting on development targets for the two other main 'themes' - engine and Engine Management System (EMS).
"For the 2006 engine, we again had to have more power and revs," he said. "For the EMS, we had difficulty in handling the two-by-two ICS [Idle Control System]. So, to achieve easier set-up at the race track, we started to develop the fly-by-wire system."
In order to achieve these goals, the following modifications to the 2005 bike were undertaken (middle picture, 'Modification from 2005'):
"With the chassis, we slightly stiffened the rear suspension mounting to have better control for tyre performance," said Tsuji. "On the engine, we changed to a shorter stroke than used in the 2005 engine and achieved more power and revs. For the EMS, we developed a fly-by-wire system to control more parameters.
"These items were working OK and we started this season..."
But Yamaha soon hit chronic chatter problems with the new chassis - prompting three stages of chassis modification throughout 2006 although, perhaps surprisingly, the engine was also upgraded on four occasions.
"This chart [middle picture, '2006 Development flow of YZR-M1'] shows the development stages throughout the 2006 season," said Tsuji. "We changed the chassis three times and the engine four times.
"As you know, we had a chassis problem at the start of the season with chattering. Through this period, we gathered a lot of data and modified the chassis. From Le Mans, we started to use the chassis to countermeasure chatter. This chassis was third generation.