The YZF is a name that guarantees: it invented the four-stroke of the modern cross, showing the way for those who followed. And now the Yamaha YZ four-stroke (with an F), is among the bikes that have dominated motocross, starting from the 1997 debut, and since 2004 has won more world titles than any other in the MX1 and MX2 classes.

The YZF have been the perfect alliance between champions of calibre such as Josh Coppins and David Philippaerts (in Mx1) in addition to local Antonio Cairoli in the MX2, who are around again in 2008 to race in the world championships.

We also add that Chad Reed has recently won the prestigious AMA-SX, and even in the World Female Championships Katherine Prumm is battling with her YZ250F: and the scene is complete.

To improve the possibility of victory, the range will undergo some developments for 2009 with the view to perfecting performance- the next generation of 450cc and 250cc four-strokes will have powerful but manageable engines.

The 2009 aim was to create a new rolling chassis that will give riders an edge in tighter corners: so more sensitivity in riding, increased speed and acceleration was needed.

Yamaha technicians have worked to increased manoeuvrability of the four-stroke motocross to give a more sensitive riding feel and agility in difficult areas, and in cornering. The work has proved fruitful and guarantees Yamaha riders an added margin in corners. New balance and suspension has also made its contribution.

Modifications have been introduced not only to increase cornering speed, but also to allow more rapid acceleration, meaning riders can come in from wide on cross and supercross tracks.

The main changes for the YZ450F are: vew black valve cover, new linkage, lighter fork (350 grams less) and some changes to the rear tyre including larger diameter axle (25mm) and re-designed spokes.

Some work on the suspension has been undertaken, the handles have four different adjustable positions, new seat work is included and a new gold-coloured chain is included. The clutch lever is shorter and easily adjustable, blue and white colours include “speed-block” graphics and the front brakes have been reinforced with alluminium.

The YZ250F includes some changes with a softer clutch, and the above elements of the YZ450F. The YZ 250 and Yz 125 have no major engine changes, with modifications instead kept to new seat material, the same gold chain and alluminium brake support, lighter wheels and “speed-block” design.

2009 will also see the YRRD (Yamaha Rinaldi Research and Development) “racing” kit for competition customers. Yamaha’s long experience in Motorcross championships and the praise from champions such as Coppins, Cairoli and Philippaerts guarantee the durability and performance of this kit with its great quality/price ratio. The YRRD Racing Range 2009 includes kits for the YZ450F, YZ250F, and the YZ125. For more information go to www.yamaha-racingparts.com.

Other models (WR450F, WR250F, YZ85/LW, TT-R50E, PW80, PW50) of the 2009 range have no technical changes so far but also include the “speed-block” graphic.

via | Yamaha Motor Italia

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