"But for handling and stability against side winds, the aerodynamics of the side view is very important too. Sometimes it is even more important than the front CDA. The problem is that these two subjects are incompatible.
"The YZR-M1 shape is developed mainly to reduce frontal CDA, but through the years we tried to find the best compromise between front and side view."
The aerodynamic data provided by Yamaha indicted that the 2002 M1 had low frontal drag, but relatively poor cross wind stability as a result. The side yaw was then reduced significantly for 2003 and 2004, at the cost of frontal drag, but for 2005 and 2006 Yamaha was able to keep the lower side yaw, while reducing frontal drag back to near the 2002 level.
Mass centralisation around the M1's centre of gravity, a vital element of optimum machine handling, was achieved by evolution of the fuel tank shape, relocation of electrical hardware and improved engine design (middle picture, 'Mass centralization').
"To achieve the best handling, mass concentration around the bike's centre of gravity is very important. Through the years, we've developed this in three main areas," stated Tsuji.
"Firstly the fuel tank. You can imagine that the fuel tank shape can help mass centralisation, but it can also help to keep minimise the weight balance difference [front to rear] between a full or empty tank .You have to remember that the [space provided by an] in-line engine is a great help in achieving this.
"Second is the location of electrical parts. We used to put these under the front panel. The ECU, logger and related parts are not heavy, but their location was a long way from the bike's centre of gravity. This was a problem. So we moved these electrical parts to the tank rail and achieved a big improvement in mass centralisation.
"Third is the engine, we try to design the engine to be as compact as possible. We always focus on finding the best location of the four axis."
The success of these improvements can be seen in the 'Result of mass centralization' diagram (middle picture) where the reduction in inertia - in terms of roll, pitch and yaw - since 2002 is shown. In real terms these reductions result in more responsive handling.
Tsuji then switched his attention to the engine, beginning with the configuration and then how the engine specification had evolved (lower picture, 'Engine configuration' and 'Evolution of engine specification').