Pros: Light weight, super power, easy to ride
Cons: smallish fuel tank, turn signals and mirrors would make it street legal
I have not been on a dirt bike for quite some time. I do recall that there is a different approach to mastering the off road beast as compared to the road bikes. Some riders have taken this to a new level, almost a science or an art form.
I was offered a chance to put one of Yamahas new WR426F into a dirt pile this past weekend. And I did my best to try and hurt myself. The almost monsoon like weather this week provided a large assortment of bogs, berms and sliding spots in the Oklahoma clay.
Yamaha has always held a spot in my heart when it came to bikes, especially dirt bikes. And this years WR426F is no exception. Having not used a kick start since I was 16 (20 years ago) I found the starting sequence awkward at first.
With a seductive length of 85.5 inches, and being only 32.6 inches wide, the WR426F will fit easily into any bike trailer, back rack or truck bed. My buddy delivered this one in an old Subaru Brat. And with a dry weight of 240 pounds, it is easily handled solo with a ramp, or by a duo just lifting it out.
The WR426F is an enduro bike with an off road setup, both in suspension and tuning. It has nearly a 40 inch seat height. And since I have only a 30 inseam I was always using my toes for balance.
This is a nearly street legal bike that really wants to be out in the dirt. Kind of like having a wolverine for a wlak in the park. You could get away with it, but the critter will be much more at home in the woods.
Using a liquid cooled, titanium valved, 426cc four stroke powerplant as a baseline, Yamaha has built a fine enduro.
Enhancements in the engine design include produces the use of a 39mm Keihin FCR flat slide carburetor with throttle position sensor (TPS). The TPS ensures exact fuel to air mixing and neck snapping throttle response. By incorporating a digital CD ignition system, the engines electronics deliver more precise and more powerful sparks to burn the fuel. It also monitors engine speed to ensure optimal timing for faster, stronger response during acceleration. And the 426 ccs come from a frugal 95 mm bore and a 60.1 mm stroke. With a mild 12.5 to 1 compression ratio, the beefy 426 rips power out whenever you touch the throttle.
Overall, the modifications provide outstanding low and midrange torque over a broad powerband. This is especially useful for off road riding. In fact, its almost as if your on a race bike out there. And for off road use the engine has received an upgrade in its armor. Engine guards on the right, left and underside offer full protection against brush, rocks and that occasional armadillo. Although, with almost 15 inches of ground clearance, I doubt you will often hit any armadillos.
By using a large capacity race specification radiator and incorporating louvers, Yamaha has ensured the WR426F has maximum cooling efficiency without cutting out too mush horsepower.
Weight reductions are everywhere on the bike. A good portion was dropped from the exhaust system. The redesigned lightweight system maximizes engine power and allows easy replacement of the oil filter.
During the revamp, Yamaha considered the woodland rider and installed a stainless steel muffler with USFS approved spark. This combination prevents forest fires and muffler corrosion at the same time.
With all that extra performance delivered by the engine, there needed to be a strong suspension to allow propulsion and to absorb the shock from the ride. Tweeks in the suspension settings help to smooth out fork and shock stroke at both ends. The twin spar frame is lightweight and incredibly strong, allowing minimal flex and razor sharp handling. The use of stronger, lightweight materials allows a swingarm that is more rigid. This aids in improving the handling, especially in the high speed turns. The rear suspension system features fully adjustable Kayaba shock with 12.4" of travel and separate adjusters for high and low speed compression damping . A lightweight 46mm inverted Kayaba cartridge fork features 11 .8" of travel with compression and rebound damping adjustability.
A larger (245mm) rear brake disc gives great stopping power. When coupled with the rear brakes, the 250mm fully floating front disc delivers stronger stopping power with unmatched controllability.
Add to this the fact that the rear subframe is removable in order to ease maintenance requirements.
The transmission is a lot better in todays dirt bikes than I remember. I used to have to fight the gears and feared a kick out in a turn, The WR426F has an easy shifting, wide ratio, five speed transmission that couples power to the chain via a multi-plate clutch geared. The clutch has so much grab that I think it would allow stump pulling. There is no loss of transfer during turns, acceleration or at the top end. I really liked the attention spent of the clutch handle. The WR426F features a race specification barrel adjuster for on the fly adjustments. No longer do you have to stop and tweek in the clutch if you notice slippage or a loose cable.
Using lightweight Excel rims (21" front, 18" rear ) provide exceptional durability and help reduce unneeded weight for optimal suspension performance. The bike came with Dunlop 739 knobbies (80/100-21 front, 110/90-19 rear) , these offer competition traction and excellent wear.
Attention to detail is demonstrated by the steering crown, seat, fuel tank, and handlebar. With wide, cleated, folding footpegs the rider has superb comfort and ground clearance. ,The strategically placed radiator shrouds create ergonomically balanced riding position . This helps ease movement and aids in weight transfer flexibility during aggressive riding. Like the kind I managed to get covered in mud in this weekend.
Even though this bike is not to be found in the city, the use of enduro lighting in front and rear could allow a quick trip to grab some milk or fill up the tank. Especially out in the boonies like where I lve. The ability to reset the tripmeter allows one to keep track of both mileage and fuel reserves. A big boon, anyone who has pushed a bike a mile or more will attest so. The 3.2 gallon tank is large enough for lengthy riding, but dont expect to cross the Rockies or the Mojave Desert on a single tank.