2002 Yamaha WR426F

Ken Hutchison | February 25, 2003
2002 - Yamaha YZ426F

Long-term WR Test

Yamaha rocked the off-road community in 1998 when it unleashed the YZ400F on an unsuspecting public, and the repercussions continue to affect the market as an ever growing onslaught of thumpers have begun to wrest control from the 2-strokes on a global scale. The Yamaha 4-strokes have proved to be plenty capable at the track, the woods and everywhere in between.

For those preferring to ride off the track, Yamaha offered up the WR version, a liquid-cooled, titanium-valve dirt bike developed to handle damn near anything a rider can throw at it other than supercross duty. Many riders buy the best motocrosser they can get their hands on without any intention of going to the track so why not just buy the bike they want to begin with. They must then spend a load of time and money developing their ultimate woods weapon by adding lights, flywheel weights spark-arrestors and anything else they think will help them survive a trip to the wilderness. The WR426 allows you to bypass that garage R&D process and go directly to the riding portion of the relationship.

A host of off-road amenities are standard issue on the WR, the most important of which would be the ever popular kickstand. An 18-inch rear wheel with 120/90-18 tire keep plenty of rubber between the earth and your rim while the 80/100-21 pulls duty up front. Fuel is stored in a 3.2 gallon tank that is a bit thick in the middle, but it didn’t bother me as much as it did the other riders that spent time with the 426. It does prohibit you from moving up over the bars as far as you can on the MX version, but it’s easy enough to live with it. Exhaust is routed through a stainless header before reaching the USFS-approved stainless steel spark-arrestor silencer unit. A lighting kit and trip meter round out the list of tangible off-road goodies. 

2002 - Yamaha YZ426F
The blue plastic often comes under fire for the unsightly white scratches and creases, but they just give the bike character.

At the heart of the WR426 is a motor which retains the 95.0 x 60.1mm bore and stroke and the 12.5:1 compression ratio of its YZ426 counterpart. A quintet of titanium valves keep fuel and spent gas heading in the right direction while a 39mm Keihin carburetor provides the proper mixture of air and fuel.

Ignition mapping has been changed from the YZ, improving low-end power delivery. The WR tuning is aimed at providing usable power down low and in the midrange, although it sacrifices the extra top-end hit you get with a YZ426. The difference in the way the two motors make power is quite noticeable when ridden back to back. The WR is decidedly tame on top-end by comparison.

Yamaha built an excellent woods-capable machine right out of the box. Well, almost right out of the box, because the WR needs a few tweaks. In stock trim the bike is super quiet, but its power production is a huge disappointment because of the noise-restrictive parts placed strategically throughout the bike. This means that it is necessary to undergo some light modifications prior to heading for the hills. Removing the air box lid lets the thumper inhale, and extracting the restrictive plug in the end of the silencer frees up the back end.

2002 - Yamaha YZ426F
If you hop on a stock WR426 you will swear it might be a TTr125…but uncork the highly restrictive exhaust and remove the throttle stop and the bike is ready to get it on.

In stock condition, the WR also has a throttle stop located at the base of the Keihin carb that only allows about half a full pull of the throttle cable. Since Yamaha offers the WR as an EPA-compliant machine, it has to meet some strict noise requirements which facilitate the need to implement those restrictions. But for best results, remove the stop and fill that orifice with a blob of silicone. Once you make these minor modifications the WR is ready to get it on. But be advised: the changes we mention here are only recommended for closed-course racing, okay.

Once the engine is freed up, it makes a ton of low-end grunt and midrange muscle. Deserts tremble at the pulsating exhaust note of the big 426cc engine as it accelerates to redline before disappearing into a distant horizon. Forests echo and quake with the resonating sound as hill climbs and single track are consumed with a twist of the wrist. Yes, dear readers, we thoroughly enjoyed riding the dirt-eating monster that is the WR426.

Making the most of the power is a wide-ratio 5-speed transmission (instead of the YZ’s close-ratio box) that has an extra-low first gear that allows the enduro bound folks to have an ample supply of tractor-pulling torque at their disposal when riding on precarious banks and steep hills that are a staple of arduous woods riding. The larger gap between ratios also pays off in a taller fifth gear for a higher top speed.

2002 - Yamaha YZ426F
The 426cc powerplant produces some of the best power available from an enduro spec machine.

A beefier clutch basket and plates borrowed from the YZ model cinch up one of the few weak links on the previous WR. It has held up well and never received one complaint from our test rider sample. Regular oil changes and adjustments certainly have helped it remain strong and consistent during months of hard riding.

The steel frame boasts identical geometry numbers with the YZ250 and 426 machines. Wheelbase is an MX-friendly 58.7 inches with 14.7 inches of ground clearance to get you over any obstacles. New for ’02 is a lighter, more rigid swingarm attached to the high- and low-speed adjustable Kayaba shock.

46mm inverted Kayaba forks are shared with the track-bred YZ models as well. They are set up a little plush for our needs right out of the box, but we have heard just the opposite from a few WR owners in our region who complained their bikes were too stiff. No matter, as there is an ample adjustment range. Once they were dialed in there was nothing to bitch about.

The front brakes of the 2001 YZ426 I previously owned howled like a beat dog from the moment it rolled off the showroom floor. I replaced the stock pads with a set of aftermarket EBCs and it took care of that complaint. The new 2002 set-up has alleviated those problems altogether with a new pad material. The 250mm disc brakes and twin-piston caliper up front provide plenty of power to slow the bike down. They never faded in the not-so-extreme conditions of woods riding and always provided consistent feedback and feel. No complaints about the 245mm rear disc brake and single piston caliper. 

2002 - Yamaha YZ426F
The WR shares Nissin brake components with the track ready YZs. That is why these brakes can be summed up in one word: Great.

As usual, the starting procedure is always an issue when it comes to the Yama-thumpahs (at least till ’03). We’ve all seen Fonseca and Ferry frantically kicking their 4-strokes after a stall as the rest of the field make their way past. The trick is just to get familiar with the starting procedure. For owners who have had a 426 for any amount of time, starting the big Single is no big deal. For new riders it can be a nightmare.

Just remember these steps: Don’t give it gas, push the piston to TDC and un-weight the kick start lever. Then pull the decompression lever and push the kick starter an inch or so past TDC. Release the decompression lever and allow the kickstarter to return to the top. Give it a swift kick and it should fire every time. If you stall after the bikes warmed up, pull the hot start prior to those instructions and it will fire right up. I know it sounds complicated, but the WR’s virtues as one of the ultimate woods bikes ever compensates for it. Honestly, though, it would be great to have the automatic compression release like that on the 2003 Yamahas and the Honda CRF450. Even better would be an electric starter.

The WR’s seat is comfortable with plenty of support for daily riding. The problem for me was the seat height. Since I boast all of a 31-inch inseam, the 39-inch-plus reach to the ground means I never get to touch both feet on terra firma.

2002 - Yamaha YZ426F
The WR is at home in the woods. The big thumper will dispatch obstacles at an alarming rate so its best to keep on guard at all times.

The stock bars have a nice bend, but a fourth-gear loop-out caused them to bend like butter upon impact – as did the left radiator. Luckily neither component broke so I was able to ride back with my ape-hanger-like set-up. A set of Renthals made themselves right at home and they look better to boot. The WR receives good marks in the appearance category, too. The blue plastic often comes under fire for the unsightly white scratches and creases, but they just give the bike character.

The conclusion:
The 2002 WR426 is a worthy addition to any stable. If you plan to spend all your time at the local track then look to the YZ class. But if you plan to ride in the woods, the desert or any place in between here and the track, then you’d do well to consider the WR. Powered by an excellent and reliable motor, it is ready for any obstacle you can find. Once you get the suspension dialed in to your riding style and become familiar with the starting ritual, there will be few complaints emanating from your pie hole.

Project Bike Hype
After spending the end of the summer riding around in strangulating dust as every bit of moisture was evaporated from our earth here in the Northwest, thanks to a drought and 500,000 acres of wildfires that swept across our land, I found myself thinking about a street legal WR, super-motard style.

Ken Hutchison

By Ken Hutchison Editor-in-Chief |Articles|Blog Posts|Articles RSS|Blog|Blog RSS The ulcers keep piling on for the warden of the MotoUSA asylum. With the inmates running rampant around the globe, Hutch has opted to get in on the madness more these days than in years past and is back in the saddle again.

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