We tested Kawasaki’s 2009 KFX450R and found that with features such as fuel injection, reverse gear and its 46-inch width, it was best suited to aggressive off-road riding. The KFX has a responsive engine with good low-end horsepower, powerful brakes and good overall construction. Unfortunately, a lack of upper-midrange and top-end horsepower, soft front suspension and a front end that can be twitchy under hard braking hold the KFX back in stock form when it comes to running rough, wide-open sections or at race speeds.
Allen Knowles from CT Racing told us he had a budget KFX450R project he’d built for ATV Rider magazine that cured its stock woes and gave it a leg up on the competition. This wasn’t an over-the-top magazine bike. CT wanted to fix the things they didn’t like about the stock machine, making it a good all-around trail bike that could also be raced in some situations.
Watch Our CT Racing KFX450R Project Test
The Build: Allen Knowles Explains CT Racing’s Approach
CT Racing Engines owner Allen Knowles walked us through the changes, starting at the front of the machine.
Calming the Front End
One of our biggest complaints with the stock KFX450R was its nervous steering under hard braking. As the front end dove, the machine could feel twitchy, particularly when an aggressive rider was trying to brake late into a rough corner.
Teixeira Tech’s adjustable upper A-arms addressed that problem while retaining the stock lower arms and the Kawasaki’s narrow trail-friendly width. The upper arms allow caster adjustment to improve straight-line stability. Their adjustment system also makes changes relatively simple: loosen the upper ball-joint nut, move the adjustment and tighten it back down, rather than taking the front end apart.
CT developed the build in stages. After testing the A-arms, Knowles still wanted a little more control in rough terrain, so he added a Blingstar steering stabilizer. The adjustable stabilizer was another reasonably priced improvement that fit the project’s budget-minded approach.
NoLeen J6 Revalved KFX450R Shocks
The Kawasaki’s stock shocks are adjustable and rebuildable, making them a good starting point for a project like this. External adjustments alone weren’t enough to produce the ride Knowles wanted, so he turned to Clark Jones at NoLeen J6 to revalve and respring the shocks.
Both the front and rear received attention. Dual-rate springs helped provide a more compliant ride over small bumps while improving resistance to bottoming on larger impacts. The small upper spring helped with initial plushness and ride height, while the main spring handled the heavier loads.
Rebuilding the stock shocks didn’t add wheel travel. The front end still had its original 8.5 inches, but the goal was to make better use of the travel already available. A complete aftermarket shock package could take the build further, but that wasn’t necessary to achieve the trail and occasional-race performance CT was after.
Tires and Wheels
Maxxis Razr tires were selected for their off-road traction and cornering performance. Their profile helped the Kawasaki feel more stable in flat turns while retaining its narrow footprint. OMF reinforcement rings added strength to the wheels, helping protect the rims from the kind of impacts that can bend a wheel and cost you air pressure on a rocky ride.
Protection
Pro Armor supplied the bumper, nerf bars and protection underneath the machine. The nerf bars combined wide footpegs with integrated heel guards, providing a secure place to stand and plenty of room behind our boots. A full-length chassis glide plate and swingarm skid plate helped protect the Kawasaki from rocks and other trail obstacles.
More Power Where the KFX450R Needed It
The stock Kawasaki delivered useful bottom-end power, but it wasn’t one of the stronger 450s as the revs climbed. CT Racing started with its exhaust system. According to Knowles, the pipe alone didn’t produce the kind of gains CT had seen on some competing 450s, so the next step was an intake cam. That added a little more than one horsepower, but the biggest breakthrough came from the intake system.
A Fuel Customs intake picked up more than three additional horsepower in CT’s testing. With the engine moving more air, the mixture became too lean on the dyno, making a Dyno Tech EFI fuel controller an important part of the combination. With the exhaust, cam, intake and fueling sorted out, Knowles reported almost 49 horsepower on CT Racing’s dyno.
Peak horsepower was only part of the story. The goal was a broad power curve that would make the Kawasaki easier and more entertaining to ride, rather than an engine that demanded constant shifting to stay on the pipe.
Making Long Rides More Comfortable
The stock KFX450R seat was another area that needed attention. Quad Tech foam and a gripper cover improved comfort, and Knowles chose a flat seat profile rather than a hump-style design so the rider could move rearward without interference.
The stock handlebar mounts were reversed to move the bars forward slightly. ASV clutch and brake levers provided adjustable reach to suit different hand sizes, with on-the-fly clutch free-play adjustment. Spider Grips added a small-diameter, comfortable grip with durable ends.
None of those changes made horsepower, but the seat, grips, levers and wide footpegs all contributed to a machine that was more comfortable to spend a full day riding.
The Test
Racing through the desert for the first time, the difference between the stock and CT-modified KFX450R was immediately apparent. Its already-good low-rpm horsepower was increased, along with a real awakening in midrange and top-end power. In tighter, technical situations, the KFX could now be shifted much less often thanks to its broader, electric-smooth powerband.
With stock tire size and gearing, the KFX now reached its top speed very quickly. We often found ourselves grabbing for another gear and felt the machine could pull an additional tooth on the countershaft sprocket for more top speed.
The tough, lower-profile Maxxis tires increased cornering stability and did a good job of getting the extra horsepower hooked into the loose desert floor. Although OMF’s wheels didn’t provide an increase in performance you could feel, we felt more secure pounding through the rocky desert with the additional rim protection.
The KFX retained its agile steering, but nearly all of the twitchy feeling had been taken out of the front end thanks to the combination of the caster-adjustable Teixeira Tech upper A-arms and Blingstar steering stabilizer.
With both the front and rear shocks revalved and resprung by NoLeen J6, the KFX450R’s suspension was greatly improved overall. Although its stock wheel travel couldn’t be increased, it felt much longer landing from jumps with a 200-pound rider on board. Despite having more bottoming resistance, the shocks remained plush through choppy desert whoops.
The formerly too-soft front suspension had really come to life, making the most of its 8.5 inches of wheel travel. Suspension action at both ends seemed well balanced. When we occasionally found its limits, it never seemed to kick or swap out. Although we’d highly recommend having both ends done, on a tight budget we’d start with the front shocks for the biggest improvement for the money.
Pro Armor’s wide-footpeg nerf bars, Quad Tech’s seat and foam, Spider Grips and ASV levers made all of the machine’s contact points more comfortable, especially for long rides.
Conclusion
In stock condition, we felt the KFX was best suited to off-road riding or racing. CT Racing and the other companies involved built on the machine’s strengths while eliminating its weaknesses. With all the components from this budget build added together, we felt this Kawasaki had what it took to win amateur classes in the GNCC series, or simply serve as the ultimate sport machine for the off-road or trail rider.
