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2007 Yamaha WR450F WR250F

Sunday, December 24, 2006
Hilde has a hard time deciding which is more impressive  the new WR lineup or Costa Rica s unreal scenery.
Hilde has a hard time deciding which is more impressive, the new WR lineup or Costa Rica's unreal scenery.
Any time an OEM drags a dozen journalists nearly 6000 miles round trip to ride some of its bikes, you can bet every last candy cane that it's for good reason. Yamaha shipped us off to Playa Hermosa on the Pacific coast of sun-drenched Costa Rica to test the latest and greatest version of its awesome WR lineup. We jumped at the chance to swap our wintertime blues for some of the hottest Blue on the off-road market.

The WR450F has won the MotoUSA 450 Enduro Shootout for the past two years running and we've constantly praised it for a level of versatility, durability and performance that exceeds its price tag. The big-bore will cost buyers an extra $400 this year (MSRP $7199) and the 250F ($6399) is an extra three hundo compared to '06. But before you fog up the computer screen with all that huffing and puffing, I can assure you that the 2007 bikes bring an equivalent amount of upgrades.

We'll hit the specifics of each bike shortly, but first a blanket preview of '07 changes that are found on Dubya-Rs big and small. By naked eye alone, the new bikes are considerably changed from last year. Top to bottom, a set of ProTaper handlebars, an ovoid headlight, new graphics, flatter seat and 2.1 gallon YZ-F-style fuel tank, aluminum frame, full-coverage plastic skid guard, quick-access airbox, massive footpegs and wave-style brake rotors add up to a visually refreshed, and attractive styling motif. The YZ-style rear fender with undertail LED taillight is extra chic in my opinion; the bikes are nice to look at, no question.

Jungle foliage is a little different from the type of trail brush we’re used to dodging. Regardless  no matter what kind of single-track you do battle with  the new WRs are very good at bobbing and weaving.
Jungle foliage is a little different from the type of trail brush we're used to dodging. Regardless, no matter what kind of single-track you do battle with, the new WRs are very good at bobbing and weaving.
Yamaha's research shows that 29% of WR owners actually race their bikes, a healthy percentage in this category of bikes, and this warranted giving its new off-roaders a racier feel and greater agility in the tighter confines of woods riding. Much of this was accomplished by utilizing proven technology and lessons learned at the motocross track with the YZ-F lineup. Both '07 WRs come with the aluminum frame that appeared last year on the MX bikes. The frame change was one of the primary mods targeted at giving the WR lineup a smaller, lighter and quicker-steering machine, a primary goal for making the bike more race-worthy out of the box.

One of the changes that came with this new alloy chassis is engine oil placement. Where it was once held in the steel front downtube, the 250F uses an oil reservoir that sits against the front of the cases between the wishbone spars and is the same version used on the 2006 YZ250F. Moving the lubricant from the upper frame to essentially the bottom of the engine drops the center of gravity and aids mass centralization, a huge issue for all these modern 4-strokes.

"A lower center of gravity really helps the bike have a lighter, more nimble feel," assures Yamaha Technician and Test Rider, Mike Ulrich.

Yamaha moved away from the external oil tank idea with the 450F and instead contains all its oil inside the new engine cases. Another trick pulled from the moto realm is the rotation of the cylinder to a more upright position.

Also like the YZ-Fs, the upper tripleclamp is forged aluminum for weight reduction and greater strength. Steering on the '07 models is much like the Yamaha boys have been pumping all along, responsive and light. Though the frame is similar to the motocross version, there are noticeable differences. A 27.4-degree rake and 4.7 inches of trail on the WR450F is lazier than the 26.8-degree/4.5-inch arrangement of the quick-handling '07 YZ450F. However, the WR250F follows a much closer pedigree to its MX cousin. Both Lites-class bikes have an identical 27 degrees of rake and 4.5 inches of trail.

New wave-style brake rotors give you the confidence and ability to go fast and stay in control.
Changes to the WR250F produce a bike that is supremely easy to ride and puts the rider in ultimate control. The smaller bike definitely has an advantage in requiring less energy to ride.
Riders will feel comfortable and in control with the 8mm-taller ProTaper bar which opens the riding position. Further expanding the cockpit are footpegs that are 11mm-wider and 5mm lower. Seat height is 0.5 inch taller on the '07 450F at 38.5 in. but the 250F has risen even less with 0.2-inch gain, and softer foam makes it easy on the butt. But the lowered pegs, raised bars and thin layout encourage the rider to stand up, as did the stunning landscapes our tour guides from Costa Rica Unbound led us through - some of the most scenic riding I've ever encountered.

As it was, the bikes we rode were able-bodied woodsmen, a handy asset on the tight single track that was overgrown with the lush, green foliage of a rainforest. The new frame gives the bike a super-narrow feel, and both machines benefit in the handling department as a result. "The WRs are the same width at the knees as the YZs," claims Ulrich.

Inside the 250F mill are a new intake camshaft profile and altered cam timing to boost low-end and midrange power. Jetting changes and revised ignition mapping complements the grunt-seeking effort. Getting power to the ground as quickly and efficiently as possible in tight situations is accomplished through a series of gearing changes. First and second gear ratios remain unchanged, but the final three cogs are closer together to ensure the little motor doesn't get bogged down. To keep the top-speed capacity on par with past years, a 50-tooth sprocket was bolted on to replace the shorter 52T of '06. Slipping through the 5-speed tranny is smooth and precise, and the gearing changes are effective at keeping the motor on the boil. 

Standing up for obstacles or just to get a better look at your surroundings is made easier than ever with a wider layout on the new WRs. Massive footpegs give plenty of support for a day on your feet.
The WR450F has had a broad, usable power delivery in years past, but mods to the engine make the bike even better down low with plenty of grunt in just about any gear or situation.
Similarly, the four-fifty has some cam profiles and timing revisions of its own, as well as the matching adjustments to the 39mm flat-slide Keihin feeder. Further internal changes feature an evenly distributed engine balancer which ups the balance factor from 65% on the 2006 to a velvety 100%. From low rpm to the upper revs the 450F is indeed a smooth motorcycle both in terms of power delivery and vibes transferred to the rider.

Changes to the intake system are mirrored on the opposite side of the cylinder with a redesigned exhaust on the 450F, all in the name of increased low and mid-range performance. Yamaha engineers hacked 37mm off the midpipe and shrunk the header 3.2mm in diameter. "What that does," explains Ulrich of the smaller header, "is gives us a little more backpressure to help the low-end."

We spent quite a bit of time on our first day sliding our way through a particularly nasty section of rainforest. The jeep road was carved into red clay soil which had recently received a tropical deluge. It was as if the rain gods hawked a giant, red loogie and the slippery goo required an easy throttle hand to avoid losing the rear end on corner exits. Both 450 and 250 machines were happy to run a gear high and chug through the jungle using the considerable yet smooth low-end muscle.

Both the 450 and 250 had some issues with carburetion, but the problem stemmed not from a mechanical shortcoming but the crappy and inconsistent quality of Costa Rican gasoline. All of the journalists experienced it to some degree where a bike would run fine in the morning and then suffer spotty performance after a refill, or vice-versa.

The 48mm Kayaba fork on the 450 is the only suspension component on either bike that hasn’t received a change in spring rates. A few clicks out on the compression adjustment had the WR450 soaking up everything our tester could find.
The 48mm Kayaba fork on the 450 is the only suspension component on either bike that hasn't received a change in spring rates. A few clicks out on the compression adjustment had the WR450 soaking up everything our tester could find.
Both the 250F and 450F come as 50-state legal machines in stock trim, and Yamaha warns that the bikes must be kept in stock condition to meet all off-road trail riding requirements. However, the WR can be de-restricted by removing the exhaust baffle and airbox snorkel, snipping the grey wire (which keeps the ignition from retarding through the midrange to limit exhaust and sound emissions), removing the throttle stop and replacing it with a YZ unit, and a GYTR jetting kit installed - big surprise. Yamaha always prepares press bikes like this because it knows that a whole freaking bunch of WR owners are going to do it - probably that 30% we mentioned earlier. The changes to our bike transformed the machine into a closed-competition model only, so keep that in mind if you like to head out for an occasional trail ride with your buddies.

Special care was taken this year to ensure that the WRs are at the forefront of the quiet Thumper movement. Claimed to run at 84db, the '07 bikes are noticeably quieter than in past years. The bike actually seems loud while you're riding it, but a lot of that sound is engine noise that was previously drowned out. At first it seems like the bike is rattling apart, but in reality it's just something we don't normally hear. Our bikes were in the 86db neighborhood without the exhaust insert, but even still, you can practically hear the digital enduro computer clicking off miles. Yamaha's in-house accessory department, GYTR, offers an alternate slip-on muffler that is raises the level to 96db while improving engine performance.

As much fun as it was bombing through Costa Rican rainforests  we’ll be nearly as anxious for any opportunity to ride the new WRs. Yamaha’s emphasis on woods-racing performance has really given these bikes a shot in the arm - and they were already very good.
As much fun as it was bombing through Costa Rican rainforests, we'll be nearly as anxious for any opportunity to ride the new WRs. Yamaha's emphasis on woods-racing performance has really given these bikes a shot in the arm - and they were already very good.
One final performance note is the addition of wave-style rotors, another YZ-F trickle-down. The 250mm front disc is the better-performing of the two and gives very good feel at the lever. The 245mm rear is less pleasurable to use but still plenty effective. This is one of the many changes that add up to what Yamaha claims is a one-pound difference in overall weight for the 250F (234 lbs dry) and two pounds on the big bike (247 lbs). "Aside from the benefit of unsprung weight," says Ulrich, "there's also the benefit of having less rotating mass around the axle."

Both 250F and 450F utilize the same suspension components with slightly different internals with altered valving. Spring rates at both ends were increased marginally (0.02 kg/mm) except in the 450F's fork which remains the same at 0.46 kg/mm. A little bit of harshness from the WR450's 48mm Kayaba led me to soften the compression four clicks up front and two in the rear to better handle sudden impacts. Other than that I was able to ride both machines and cover all types of terrain with a supple, well-balanced ride on stock settings and factory sag. The bikes we rode didn't feel a whole lot different than last year which means the suspenders are good stuff.

Yamaha wanted to put in an impressive debut for the '07 WR machines and Costa Rica was certainly the place to do it. From the perspective of a man who has traveled no wider than spitting distance into Canada and Mexico, the fact that I can't decide which left a more lasting impression, the country or the machinery, says something special about the Yamahas. The power on both bikes is easy to use and offers plenty from each respective displacement. New chassis offer a racier feel and look but the benefits will still translate for even the most casual trail riders.

Here at MotoUSA, we've always been fond of the WR lineup, and the new Blue keeps on impressing. One thing's for sure, after spending three days aboard these capable machines, I decided that the whole Costa Rica experience was definitely better aboard the 2007 off-road Yammies. Chances are this will be true wherever you ride.

Yamaha’s list of changes adds up to some impressive results. The WR might just be the biggest tree in the woods for 2007.
Yamaha's list of changes adds up to some impressive results. The WR might just be the biggest tree in the woods for 2007.
The Inside Line
A quick-list of '07 features.

WR250F:
New intake cam and oil tank location
Revised gear ratios

WR450F:
New engine and balancer
New integrated oil tank location
New camshafts
New exhaust system

Both:
New aluminum frame
New body styling
New LED taillight
New quick-access airbox
New wave-style disc brake rotors
New ProTaper handlebars
New wider footpegs
New full-coverage skid plate
New radiator with bracing
New radiator louvers
New forged top triple and handlebar clamps
New seat cushion design
Sealed O-ring chain


Talk about the 2007 Yamaha WRs in the Forum.
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Comments
Chad Reed -07 wr450  January 8, 2010 08:39 AM
great stock bike but when you add the fmf powercore 4(slip on), its even better. just got the pipe for x mas and its awesome
Ted Kinsey Jr. -Factory exhaust  April 6, 2009 05:44 AM
How do I pull the factory exhaust apart?