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Yamaha set-up report – Motegi
13 September 2005
Motegi is unsurpassed in its design and circuit quality - the surface is seamlessly smooth, offering high levels of grip, and the facilities at the Honda built circuit are exceptional.
Yet, despite this high attention to technical detail the Motegi layout is far from being a technically challenging circuit.
The track can be characterised as a series of 'drag strips', linked together by continual radius second gear corners, a layout that isn't liked by many and disliked by more. Even so it is still technically challenging enough that outright power isn't the be-all and end-all when it comes to winning races.
In fact in some respects too much aggressive power can be a hindrance at this particular venue. As a result this should prove to be of benefit to the 2005 YZR-M1, which beside shear horsepower also has a very predictable powerband with an excellent 'throttle linearity'.
This performance trait is essential since most of the +230 horsepower will be driven through to the rear wheel on the exit of second and third gear corners, only moments after completing some rather heavy braking.
This combination of hard braking to hard acceleration complicates things further with the aggressive weight transfer being a catalyst for instability. For this reason a balanced and usable base geometry will be the focus point for those riding the M1.
The main aim in both instances (acceleration and braking) is to cater for the aggressive weight transfer by minimizing the pitching effect. To do this the basic chassis package won't be too far removed from what was run during the Le Mans test earlier in the year.
The rear of the bike will be slightly lower and the front set slightly higher, when compared to other circuits, to offer the braking stability needed - reducing the likelihood of the rear wheel leaving the tarmac.
The front fork springs will boast a slightly higher spring rate, but unlike Le Mans, the damping won't have to cater for any real bumps during the period the front forks are compressed.
The rear shock on the other hand will run a slightly softer spring with a high amount of preload. This will help to offer the feel and consistency under power while preventing the bike from squatting to the point which can cause it to run wide or, in extreme circumstances, wheelie.
At the same time suspension technicians will also have to consider the effects of the rear shock pumping through its stroke - a common concern on a track where the bike is driving hard off a slow speed hairpin.
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