Kawasaki 2008 KFX450R

Its hard to imagine today, that only a dozen or so years ago the ATV manufacturers were saying that the Sport ATV market was flat and that little or no growth was anticipated.  Yet not only has the Sport ATV market grown significantly, we are beginning to see an exciting trend of factory-built ATVs bred specifically to be competitive on the race track.  Why is this exciting?  Because it brings competitive racing within the financial reach of the average person.   No longer is it necessary to replace the frame, major suspension components and nearly rebuild the ATV from the ground up in order to win races.  These factory-built race-ready ATVs level the playing field and open the doors to a world of possibilities.

We had an opportunity to test one of these exciting new high-performance race ATVs, when Kawasaki invited us to a Press Introduction held at Carolina Adventure World in South Carolina.   The star of the day was Kawasaki’s new 2008 KFX450R.  Kawasaki had one very clear objective when they introduced the KFX450R  — to flat-out smoke the competition on the track.  Let’s take a critical look at this ATV and see if it has what it takes to grab the hole-shot on the competition.

Potent Power  

The performance capability of an ATV begins with the ever-important engine.  Kawasaki chose their potent, race-proven, KX450F 4-stroke motocross engine as the foundation upon which to build their race ATV engine. An ATV, of course, is heavier than a motorcycle which means that the engine has to overcome the additional weight in an ATV application as well as additional rolling resistance.  Therefore, low and mid-range torque had to be increased if the ATV was to be competitive.  Kawasaki achieved their goal by replacing the carburetor with an altitude and temperature compensating digital electronic fuel injection system — which had the added benefit of also improving overall throttle response. We found that the ATV had very impressive acceleration off the line and when hammering hard in the corners.  

The 449cc engine revs to between 10,500 and 11,000 rpm.  Although, peak torque is measured at about 7,500 RPM. As the limit on the maximum sustainable engine RPM is increased on a 4-stroke engine, proper design of the valve train becomes correspondingly more critical. The KFX has an auto adjusting cam tensioner which keeps the cam chain taut.  Ultra light-weight titanium valves reduce moving mass which, aided by progressively-wound valve springs, keeps valve-float in check at the higher RPMs.

To help the big thumper breath freely and efficiently, Kawasaki provided a large volume air box, a polished intake port and a low restriction exhaust system (featuring a titanium header pipe).  As you can begin to see, this is an engine designed from the ground up to provide ultimate performance, in a lightweight package, without sacrificing durability.   We were happy to see that, while light-weight was a definite factor in the overall design goals, Kawasaki didn’t go overboard and sacrifice a reverse gear for the sake of saving weight. Instead, weight was saved by using titanium and aluminum wherever possible which gave the engineers room to incorporate all the goodies that the discerning racer requires. 

Frame and Suspension

We’re giving Kawasaki major kudos for one of the best looking frames that we have seen on a production ATV.  It’s a borderline work of art.  The KFX’s frame is fabricated entirely from aluminum and weighs in at a mere 26 pounds.  That’s about 20% lighter than a comparable steel frame!  Yet Kawasaki claims the frame is very rigid for excellent roll resistance.  The complexity of the frame requires that it be welded by hand during assembly at the factory.  Craftsmanship that went into the frame’s construction is clearly evident throughout.  The KFX also has a removable sub-frame.

The front-end uses a single box-tube lower frame front suspension.  The narrow front allows the A-arms to be longer which results in a longer suspension stroke.  This minimizes camber change when compressed and helps improve tracking during high speed corners.  The longer travel also helps keep the wheels in constant contact with the ground, when traversing rough terrain.  If you expect to turn, you just might want your front wheels on the ground!

Front suspension travel is a respectable 8.50 inches.   KYB shocks with dual-rate springs also provide 20-way compression and rebound adjustment.  The adjustable factory shocks should serve most riders extremely well.

In the rear, keeping with the lightweight objective, the KFX has a cast-aluminum swingarm which was specially designed to be extremely rigid.   So how do all of these lightweight components affect the performance profile of the KFX450?  We’ve all heard of Newton’s first law which states that an object in motion tends to stay in motion.  Why this is relevant to a suspension system, is because the suspension moves in one direction until it reaches the extent of its travel and then it must change direction and move the opposite direction.  The more mass (weight) contained in the suspension system the more difficult it becomes to stop (the moving mass) and reverse the travel of the suspension.  Thus, a lightweight aluminum swingarm with lightweight shocks, wheels and tires reduces the overall moving mass of the suspension system — which translates into a much quicker responding suspension and consequently reduces rider fatigue.   The reduced weight also makes the ATV feel more nimble and responsive in turns, which adds to the overall excitement of riding the KFX.  So you begin to see that as Kawasaki designed the KFX it was designed as a complete performance package.  Nothing was spared, no shortcuts were taken.   

Like the front, the rear also uses a KYB shock with dual rate springs and 20-way adjustable compression and rebound dampening.  With a full 10 inches of rear suspension travel, the KFX is poised to tackle the toughest terrain.   

Kawasaki is the largest manufacturer of ATV wheels in the world.  In fact, they supply wheels for their competition’s ATVs!  So it should come as no surprise then that the wheels on the KFX are extremely well-built.  Both the front and rear aluminum wheels feature integrated reinforcing rings to prevent buckling under heavy impact.  The reinforcing rings are drilled to reduce weight and to shed both water and mud that may accumulate inside the wheel.  The lip on the wheels have been rolled to provide added strength at the bead.  We think these wheels should prove to be very durable in competition.

To reduce unsprung weight in the rear, Kawasaki installed a 200mm petal-type disc brake with a single-piston caliper.  Whereas, up front dual 163mm discs with twin-piston calipers were utilized to provide the high performance stopping power required for an ATV capable of this class of competition.  

Test Ride

  We couldn’t wait to jump on board the KFX450 and take to the track and to the woods.  A twist of the ignition key and the deep, throaty sound of the 450 sprang to life.  We slipped the smoothly shifting 5-speed transmission into first gear, raised the throttle, eased out the clutch and immediately killed the engine.  Lesson number 1 – the KFX is bred to race and has a very tall first gear meant to provide that hole-shot advantage.  You have to learn to ride the KFX, which means being a little more aggressive than your average sport ATV.  Suitably humbled, we cracked the throttle and left the camp behind buried in dust and a spray of gravel.

Ergonomically, the KFX450 feels just plain sweet.  Tapered Renthal FAT-BAR handlebars are perfectly positioned and provide a solid feel to the bike.  The narrow seat is smooth on the sides but textured on top for added grip so that you don’t feel like you’re constantly sliding forward into the gas tank.   The gas tank is also narrow at the back and somewhat flat on the sides.  Which means that you can lay the inside of your leg up against the tank for added leverage when cornering hard.  And corner hard we did!  It didn’t take long for us to gain an appreciation for the super low center of gravity that made the KFX feel very predictable when cornering or even cornering off-camber.  It’s a real hoot to charge into a corner, tap the brakes, lay your leg up against the side of the tank, pitch the ATV to the inside and then lay the smack down on the throttle as you literally rocket out of the turns!  Its like riding a rocket on wheels, yet you always felt like you had good control.  In the entire time that we tested the KFX, we never felt like it might do something ugly or unpredictable.  The careful engineering that went into the KFX was clearly evident in the phenomenal handling performance.

We liked the fact that the KFX didn’t tend to want to wheelie of its own accord when cresting hills.  The forward to backward weight bias seemed about perfect on the ATV.  The front was heavy enough to stay put, yet with a little bit of coaxing could be made to easily loft on demand.  Throttle response was almost instantaneous and the power-band was wide and strong throughout.  The wide power-band meant that you could tackle rough terrain in a tall gear with confidence that you had plenty of power at your disposal when the time came to quicken the pace.

In the interest of full disclosure, I have to admit that at 45 years of age this editor isn’t capable of testing the suspension by doubling a tabletop – at least not without coming out unscathed.   Those maneuvers require weekly practice and are best left to the pros.  The KFX450R is capable of a performance level well beyond my ability.  However, we had Team Green Factory Racer Jason Luburgh on hand to demo the full capabilities of the KFX450R.  We encourage you to watch the videos and see for yourself how the ATV performs on the track.

One issue we ran into while testing the KFX450R had to do with hard starting.  If you killed the engine, the KFX was extremely hard to start.  It would eventually start, but not without a great deal of grinding on the starter.  Initially, we thought perhaps the problem was limited to our evaluation unit.  However, we asked one of the Kawasaki racers about it and he said that if we were to turn the key off and back on that it would start easier.  We tried the trick and the engine fired right up.  Whatever reset happened by turning off the key, seemed to make a difference.  We have not heard of other complaints of this nature from the other Editors, but our evaluation machine did give us some trouble.

Conclusion

The KFX450R is purpose-built to be highly competitive in stock form on the race track.  In fact, you would be hard pressed to find a stock ATV from another manufacturer that would give you the same odds of winning in the GNC circuit.  The KFX450R is a winning ATV. 

However, if your goal is to race GNCC or simply to have a high performance ATV to take to the trails – then some modifications to the KFX450R may be in order.  Unless we were riding very fast, we noticed that the KFX tended to want to high-center on the rear disc brake rotor when we encountered ruts. For non-track riding, you may find that you want to install some taller tires on the rear and then change the gearing to off-set the increased tire size.  The taller tires will raise the center-of-gravity a bit, but it may be a fair trade in order to gain some additional  ground clearance.  Add body armor and taller tires and we think the KFX is going to be a major competitor on the GNCC circuit this year.

The bottom line is that the KFX450R is blazingly fast with suspension and handling characteristics that warrant a serious look from anyone looking to purchase a high performance ATV.

Available in several colors, the two-color  Lime Green / Super Black and two-color Bright White / Super Black models retail for ,399.00.  The single color Super Black model retails for ,599.00