YAMAHA RELEASES 2007 YZ250F

Yamaha Release 2007 YZ250F and YZ250F SE

The newly released 2007 model is available in two guises – Yamaha Blue/White and Special Edition White/Silver – and features a number of significant improvements aimed at further boosting engine performance and delivering even lighter handling qualities.

 YAMAHA RELEASE 2007 YZ250F

2007 YZ250F Image copyright Yamaha 2006

Using the most advanced race-bred technology developed from Grand Prix winning MX1 and MX2 race programmes, Yamaha’s engineers have further refined the winning YZ250F for the new season.

The newly released 2007 model is available in two guises – Yamaha Blue/White and Special Edition White/Silver – and features a number of significant improvements aimed at further boosting engine performance and delivering even lighter handling qualities.

Nothing comes close to matching the YZF’s track record, and the new features and advanced technology introduced for 2007 are aimed at reinforcing and extending Yamaha’s position as the leading manufacturer of race-winning motocross machinery. The YZ250F made an indelible mark on the competition when it totally dominated the 2005 MX2 World Championship, taking the first three places overall (and five out of the top seven), earning Yamaha the 2005 MX2  Manufacturers’ Championship.

With its combination of a rider-friendly power delivery, class-leading handling and lightweight steering, it is easy to see why the YZ250F has become one of the dominant bikes in the MX2 category. And development continues for the 2007 model.

YZ250F ENGINE

Although the basic architecture of this MXGP-winning 5-valve DOHC engine remains the same, a wide range of improvements to the intake, exhaust and ignition systems ensures even greater performance at high rpm and also in the over-rev range. These changes include a redesigned diffuser pipe, modified carburettor air vent passage, and new carburettor settings.

The YZ250F is already renowned for its lightweight handling qualities, and to further enhance this reputation the 2007 model benefits from a revised engine mounting angle. In effect the engine has been rotated around the drive axis so that the cylinder is more upright.

This change, together with the use of a range of new components including a lightweight engine guard ensures even lighter feeling handling. Further weight savings are achieved with the use of a new magnesium crankcase cover which is 168g lighter than the previous design.

The dry sump engine features a separate oil tank positioned in front of the engine, and for 2007 a newly designed tank is fitted, featuring an additional internal partition which improves the oil/air separation. This has allowed our engineers to reduce the engine oil volume by 100cc, thereby saving weight.

 
2007 YZ250F Engine Technical Highlights

·  Liquid cooled 250cc 4-stroke
·  DOHC, 5-valve
·  Bore x stroke 77.0mm x 53.6mm
·  Revised carburettor settings
·  Optimised intake, exhaust and ignition settings
·  Revised engine mounting angle
·  Magnesium crankcase cover
·  New oil tank with reduced volume

YZ250F CHASSIS

In order to accommodate the more upright engine angle, the YZ250F’s frame has been modified, and the head pipe is now slightly closer to the rider. The frame’s rigidity balance has also been modified by the use of   a smaller diameter engine mounting bolt, while the engine mounting   plates are also redesigned to allow for the new engine mounting angle.  

The effect of these changes is to give a slightly more compact riding position, which makes for improved handling qualities, particularly when entering turns. Any weight reduction is significant, but weight saved at an extremity of the machine – or from any part of the unsprung chassis – reaps the greatest rewards in terms of enhanced handling performance.

Featuring irregular shaped holes, the wave type discs not only reduce weight, they also enhance braking performance, and can also offer improved pad cleaning properties in muddy conditions. Further weight savings are made with the use of a newly designed brake hose.

Further weight reductions have been achieved by the use of a new compact front brake caliper. By reducing the piston size and redesigning the master cylinder and brake lever, we have been able to reduce overall weight by 228g, while at the same time increasing braking performance.

The 48mm Kayaba front forks have also shed some weight for 2007, and now feature new outer tubes which are lighter, and offer a revised rigidity balance for improved handling qualities. In addition, the YZ250F also benefits from new front axle brackets. The new axle brackets offer a better balance, and complement the new front brake caliper to give progressive and controllable braking performance. Both the upper and lower triple clamps are new for 2007, and are now manufactured from forged aluminium, compared to the cast design used in 2006.

Further weight savings are made by the fitment of shorter fork clamp bolts in the upper and lower triple clamps, and the handlebar mounts feature a smaller diameter M10 fastening bolt. Not only do the forged clamps and associated parts reduce overall weight, but their revised rigidity also helps contribute to the feeling of lighter steering that enhances overall ride quality. New Pro Taper handlebars are used to achieve an improved riding position and give an enhanced appearance. The bulged section also features useful reference marks allowing the rider to experiment with different bar positions.

The innovative rear shock with its titanium spring has been lengthened by 1.5mm for 2007 to give a slightly higher ride height to achieve an even lighter handling feeling, and the use of new aluminium components in its construction reduces overall weight. Yet more weight has been shaved by lightening more than fifty bolts, and the surface coating of many nuts and bolts is now stainless for improved appearance.

Special Edition White YZ250F Image copyright Yamaha 2006

2007 YZ450F Chassis Technical Highlights

·  New lightweight forged aluminium triple clamps
·  New wave type discs
·  New lightweight rear shock
·  Range of stainless and lightweight parts
·  New Pro Taper handlebars

RRP for 2007 remains the same at $10,299 and the SE White Silver model costs a fraction more at $10,399.