As the machine to beat in the national supercross and motocross championships, the release of Yamaha?s new 2009 YZ series, the YZ250F and YZ450F (and later to be followed by the 2009 YZ85 and YZ125 in September), is likely to be the talk of the paddock for some months to come.
In case you?re unaware, the 449cc liquid-cooled 5V four-stroke YZ450F is currently leading both the 2008 World and Australian series championships.For 2009, Yamaha engineers have concentrated on giving the new YZ series even better ?tight curve performance?. As Yamaha says, ?Cornering is where races are won and lost. For 2009, the YZs have been developed with a particular focus on quick cornering performance in tight curves.?
To this end, Yamaha has worked to reduce weight to a minimum while optimising rigidity, balance and traction. In the YZ450F this has resulted in a new lightweight swingarm which is asymmetrical in cross-section for greater lateral rigidity, while weighing-in 350g lighter than the current model. The cast parts of the pivot end have also been redesigned for lighter weight.
To also reduce un-sprung weight (and assist cornering performance), there is also a new rear hub that is 180g lighter than the existing unit. New front and rear suspension settings, adjustable bars (four positions) and a new lightweight DID (non-seal) 520DMA2 chain with premium-look gold plate finish, head up a host of improvements designed to extend durability and cornering performance.
To keep the neighbours happy, both units also feature new full-power low-decibel mufflers (Euro-spec type) to maintain high levels of power while keeping within noise limits. The YZ250F also gets a new lighter clutch operation with design and spec changes to improve the feel.
Slight revisions, but even more reason for dirt bikers to love the ?benchmark for the class? YZ series.