Stephen Ross takes a look at the all new 2007 Yamaha WR250F.
Our test bike for the day was the actual bike used by Sawyers sponsored rider Hazel Rushworth in the Taupo International Six-Day Enduro. The Manawatu farm girl was one of only two Kiwi female competitors. Hazel is taking the New Zealand off-road scene by storm and at only 21 years of age her future will be exciting to watch.
After several years refining and developing the original 2001 WR250F model, Yamaha have somewhat started again with an entirely new platform. At first glance the biggest and most obvious change is the move to an aluminium frame. A step that was expected with the success of the YZ series moving to aluminium in recent years.
Apart from the benefits of weight reduction, the new frame has allowed the engineers to move components around slightly and has centralised and lowered the mass for better handling. The balancing of their bikes is a focus for Yamaha and is where much of the development is centred.
It’s been over a decade since rival Honda first took their off-road bikes to aluminium frames. Although ground breaking technology at the time, the bikes were known for being pretty rigid and jarring with all the bumps and vibrations being transferred to the rider. After much development, Honda now have a great frame and considering Yamaha have only recently taken a step in the same direction, it was a step big enough to put them on par with Honda.
The only change to the water cooled 249cc four stroke engine was reworking of the double over head camshafts. Together with a new exhaust and carburetion system, the new bike has more low and midrange power than on previous models. The noticeable difference to the 2006 model was the increase in responsiveness. The power delivery was still true to character being smooth and controllable.
A change to the transmission ratios has given the 2007 gearbox a wider first through to third gear and a closer ratio changing up to fourth and fifth gears. This change allows the bike to sit within the optimum rev range when going through the taller gears.
We immediately noticed the new "wave style" brake rotors and were surprised at how much stronger the braking performance seemed. An advantage of this style is the reduction from the all important unsprung weight.
A plastic engine guard replaces the slightly heavier aluminium version, reducing the weight. What it loses in aesthetic appeal it will most likely may make up in the functionality as the new guard is less likely to collect mud and dirt.
With the new frame more rigid, the adjustable Kayaba shocks have been slightly revised to compensate and the rear swing arm adopts the YZ style linkage.
Nice new touches include a "Dzus" quick release air box panel, a very useful digital enduro computer and now an LED rear taillight.
Overall, when you count up all the changes on this model you would expect it to feel different, but it still has similar handling and power characteristics.
It’s still a fun, easy to ride bike that has proven it can take a thrashing from a kiwi farm girl and keep on ticking. The WR250F hits the market early next year.
Engine type: Liquid-cooled, five-valve, DOHC, four-stroke with titanium valves
Bore & Stroke: 77.0 x 53.6mm
Compression: 12.5 : 1
Starter system: Electric and Kick
Carburation: Keihin FCR-MX37/1
Ignition: Digital CDI
Transmission: Constant mesh, five-speed
Final Transmission: Chain drive
Fuel tank: 8-litre
Seat Height: 990mm
Dry weight: 106kg
Suspension Front: Telescopic fork; 300mm travel
Suspension Rear: Swing arm, link suspension; 310mm travel
Brakes Front: 250mm floating disc
Brakes Rear: 245mm disc
Tyres Front: 80/100 -21 - 51M
Tyres Rear: 130/90 -18 - 69R