2006 Kawasaki KX250F First Ride

JC Hilderbrand | September 14, 2005
2-stroke killer  Electing to cut the KX125 from its  06 lineup  the new 250F is the result of Kawasaki s sole small-bore effort. It came out pretty nice to say the least.

Kawasaki started off in 2004 at the bottom of the 4-stroke heap as the last of the Japanese manufacturers to develop a tiddler-class thumper. However, the original KX250F quickly made its mark with Ivan Tedesco winning all but one round of the 2004 AMA 125 West regional Supercross on the way to the championship and Darcy Lange capturing the Arenacross title to cap off a great first year for the KX250F.

The ’05 season looks to wind up even better with Lange and Tedesco repeating as champs, and Hot Sauce’s Monster/Pro-Circuit Kawasaki teammate Grant Langston cleaning house in the East Coast Supercross series. Unless Tedesco somehow manages to blow a 35-point lead in the final round of the AMA 125 Motocross series, the KX250F will add another AMA championship for a sophomore season total of six national titles. Not a bad start.

Kawasaki is swinging for the fence in 2006, opting to completely re-design an already stellar 250F. For 2006, Kawasaki has split ways with Suzuki following a two-year stint of coordinated development with the yellow brand. In an industry-shaking move, Kawi became the first manufacturer to pull its 125cc 2-stroke from the American market. Available in Europe, Canada and other markets, the ’06 KX125 is identical to the ’05 model with the exception of new color and graphics. However, U.S. racers will have to smuggle one from across the border in order to get their hands on an ’06. Directing R&D efforts instead to the KX250F, engineers were able to focus their efforts on creating a bike they boast is “uniquely Kawasaki.”

With blue skies overhead and a smile on MCUSA s new dirt guy JC s mug  the 2006 Kawasaki KX250F was ready to stir up some roost.
With blue skies overhead and a smile on MCUSA’s new dirt guy JC’s mug, the 2006 Kawasaki KX250F was ready to stir up some roost.

Team Green engineers have developed the bike from the ground up, and the result, as we discovered at the legendary Castillo Ranch, is nothing short of astounding. We came away knowing one thing for certain: This bike rips!

Getting the hang of Kawasaki’s newest offering was a snap. Before reaching the first corner, the 250F demonstrated in eye-watering fashion that its new powerplant is loaded with torque. Low and mid-range power is abundant thanks to some changes in the intake and exhaust ports as well as a new combustion chamber.

In only a short time I was focusing almost solely on trying to unlock my fingers from the handlebars as my arms pumped up solid leaving me helplessly stranded in third gear. The Kawi continued to impress me with its burly powerband, providing more than enough grunt despite my lazy shifting. On a track with as many elevation changes as Castillo Ranch, this might spell trouble for some smaller displacement bikes, but the KXF pulled even the steepest hills with ease, requiring only minimal clutch work from my leaden arms.

Kawasaki engineers boosted the compression ratio to 13.5:1 compared to last year’s 12.6:1. To handle the added stress, the piston crown is beefed for more reliability under increased power. New rev-limiter settings and changes to the CDI-controlled timing allow the Kawi to be ridden longer in each gear thanks to extended over-rev capabilities. The only place where I wanted to stretch more out of the motor came on high-rpm, uphill shifts. Despite the higher compression ratio, the KX’s automatic decompression system makes starting the KXF easy enough to do by hand. Literally.

Oozing with usable power, blasting out of corners and ripping off the start gate are a cinch on the little green monster. Even soft, loamy corners couldn’t bog out the motor, barring rider error. One of many nice features at Castillo Ranch is a concrete start pad, a technical challenge that puts a rider’s clutch skills to the test. Where a 2-stroke motor’s hard power hit often results in wheelspin, even a novice rider can launch the 250F without spinning off the gate. Excellent torque and superb rear-wheel traction made for effective second-gear starts despite my 180 pounds. The unfortunate 125 rider who starts next to a KXF should be mindful of the high-velocity soil sample that’s on its way. 

Renthals make a nice addition for  06  replacing the chincy steel bars of yesteryear. Quality levers add to rider comfort.
Renthal bars make a nice addition for ’06, replacing the chintzy steel bars of yesteryear. Quality levers add to rider comfort.

Getting the power to the ground was a main technical focus on the new KXF. Kawasaki tweaked the cylinder into a more vertical position, raised the swingarm pivot 3mm and re-worked the linkage to improve rear-wheel traction. Also, new on the rear end for the first time ever is a Showa shock purposely dialed for the new swingarm and linkage specs. Up front is a set of twin-chamber Showa forks, completing the monumental change from Kayaba units that have graced the KX line since its inception.

Utilizing a twin-chamber fork design separates oil and air inside the fork for consistent damping throughout long motos. The 47mm inverted fork provides 12.4 inches of travel over a new Bridgestone M401. The rear shock features both high- and low-speed compression damping as well as 17 clicks of rebound adjustments and 12.2 inches of travel. Bridgestone’s M402, a burlier version of the vastly popular M78, handles roosting duties out back.

Another first for Team Green is the twin-spar aluminum perimeter frame. The company has been using perimeter frames on its KX line since 1990, but the new aluminum system shaves 2.2 pounds off the ’05 steel version. Engineers used a blend of techniques, welding forged, cast and extruded aluminum to create the necessary rigidity but with flex in the frame where needed. The forged bits, strongest of all, are used at the steering head, lower main frame rails and at the downtube junction where it splits into two smaller extruded rails that encase the engine.

In an effort to calm the KXF’s steering, Kawasaki has added a significant 1.2 degree of rake, now up to 27.7 degrees. Trail, too, has been added, going up 0.4 inch to 4.7 inches. Despite a slight tendency for the front end to push through corners, the KXF turns exceptionally well. Good traction in the rear and a slightly top-heavy feel lends the KXF to railing outside berms. The tipping sensation disappears with more speed carried into the turn, and mid-corner line changes are fairly easy, especially on inside-out moves.

The new aluminum frame saves 2.2 pounds compared to the ’05 model. The twin-spar unit has also been reworked to provide a thinner ride and better ergos.
The new aluminum frame saves 2.2 pounds compared to the ’05 model. The twin-spar unit features a mix of forgings (pink), castings (gold) and extrusions (blue).

Braking into corners is a cinch with the new petal-style rotors providing powerful stopping power. A 250mm disc mounted to a dual-piston caliper gives the front end a solid and reliable feel. The rear is outfitted with a 240mm disc and single-piston caliper. Both brakes resisted fade throughout the day and feel at the levers was predictable.

Clutch action was smooth at the fingers as well. A close-ratio, 5-speed tranny spins a more durable countershaft that powers 13/48 final gearing. For additional strength and reliability, the output shaft has a wider diameter and internal gearing is beefier for ’06. Bigger components equal more weight, so the new model has the same 204-pound claimed dry weight as the 2005 bike, even with the lighter aluminum frame.

Searching for a narrower chassis, Kawasaki squeezed the new Denso radiator into a slimmer, high-capacity shape. The rad has the same capacity as in ’05, but Kawasaki claims better efficiency by using more tightly packed cores. Also aiding durability is a new oil pump that offers a 20% increase in flow.

The biggest problem for me on the ’06 KX250F was our test bike’s tendency to push its front end in corners. As the day wore on and I became more aggressive, the problem subsided a bit but never disappeared. A few clicks on the suspension adjustments or swapping the front tire would likely attenuate this condition. The new Showas otherwise worked flawlessly.

Watching a jump landing come and go as you sail over it is seldom a fun thing to experience, but the fork handled all flat and hard landings smoothly. Excellent bottoming resistance combined with plush action on smaller bumps makes for a great overall package. We adjusted the rear-end sag to accommodate my weight, and from then on Kawasaki’s baseline suspension settings worked well. The front end never deflected on rough sweepers or square-edged holes, and the new shock is just all-around sweet. With its sag set at 103mm, it soaked up bumps while accelerating and under braking, and not once did the rear end spring crazy-assed off a jump face, much to my delight. As the track roughened up, the rear only got better. Some personal adjustments are needed to take full advantage of what the shock has to offer, but stock settings provide a great starting point. 

Kevin Duke  MCUSA s So-Cal street fiend couldn t contain himself at the Kawi press intro. The gorgeous Castillo loam and a stable of fresh 250Fs was simply too much to resist.
Kevin Duke, MCUSA’s So-Cal street fiend couldn’t contain himself at the Kawi press intro. The gorgeous Castillo loam and a stable of fresh 250Fs was simply too much to resist.

The 250-effer’s suspension is nothing if not predictable. Like any bike, fine-tuning is a must, but the stock system does everything well and never surprises you despite the conditions. Exceptional inline stability and solid cornering characteristics make the bike super confidence inspiring. Our take on the suspension’s performance on a Supercross-style track will have to wait, as we only sampled the KXF on Castillo’s motocross-style track.

Moving around on the bike is easy with a new seat design and slimmer frame. Footpeg width is virtually the same as last year’s, but the frame narrows through the upper boot area and then widens again at the knees for ample grip. Kawasaki claims that the frame is thinner overall than last year, and could have been thinner, but they intentionally kept the pegs and knee areas wider to maximize gripping potential. The setup works as the KXF is easy to hold onto with your legs for more control and rider input.

The bike is definitely thin feeling and riding position comfortable, but 125 converts will still long for a tiddler physique. When I first straddled the 250F, the pegs felt too high for my taste. However, rather than being uncomfortable on the track, the layout is just the opposite. The peg location forces your knees into place for optimal gripping, and promotes an aggressive stance.

Clinging with your knees is necessary both on the ground and in the air. Getting all crusty on a bike just doesn’t happen for me unless it’s in my shorts, but even my minimal jumping skills were magnified on the KXF. Riding the bike for the first time, I was startled by a significant lack of boner-airs. The wheels hooked up and tracked straight again on crossed-up landings, a tribute to the excellent suspension and more conservative steering geometry.

Two-part shrouds add color and options for  06. Aftermarket companies are going to have a heyday with color schemes for the KXF. The holes on the top shroud not only give character  but are said to aid in cooling.
Two-part shrouds add color and options for ’06. Aftermarket companies are going to have a heyday with color schemes for the KXF. The holes on the top shroud not only give character, but are said to aid in cooling.

While I wasn’t able to push the 250Fs airborne capabilities to their fullest, Team Green hotshot and 2005 Loretta Lynn’s 250 Open A class winner, Scott Simon, was on hand to demonstrate the Kawi’s whipability. This thing can get flat.

Though not a Mulisha recruit, I still like to see black dirt bikes. Heeding the Monster/Pro-Circuit team’s bitchin’ graphics, Kawi’s two-piece shrouds in black and green are straight-up wicked. The dark plastic shows scratches after the first ride, and graphic companies might struggle with the holes near the gas cap, but to hell with it. Kawasaki’s new styling will draw looks left and right in the pits, and on the track.

Renthal bars and new handgrips cap off the rider department, but make for a sweet-and-sour combination. Having quality aluminum bars as stock equipment saves both time and money in upgrading a new steed, definitely a plus. However, the grips, shorter this year, are hard and provide little shock or vibration absorption. With a $5899 price tag, it would also have been nice if Kawasaki had made the switch to an aluminum throttle tube rather than the stock plastic piece. Chances are the bars will outlast both the throttle and grips. The F gets another nod in ’06 for the addition of an aluminum skid plate.

Finding things to complain about on the 2006 KX250F is no simple task. What it boils down to here are basically just a few control issues, tire selection and having enough time to dial in the suspension. To address the issue of personal preference Kawasaki also offers a number of optional OEM accessory parts that will be available at dealers. Oversized bar clamps, optional fork and shock springs and a 20-inch front wheel, among other options, allow KXF buyers to trick out their ride without ever buying aftermarket. Nice.

Even though the bike weighs exactly the same as it did in ’05  it wouldn’t have happened if the new wheels didn’t shave over a pound of unsprung weight.
Even though the bike weighs exactly the same as it did in ’05, it wouldn’t have happened if the new wheels didn’t shave over a pound of unsprung weight.

Kawasaki may have taken a slight blow in being the first manufacturer to drop a 125cc MXer from its lineup, but the added resources it freed for developing the KX250F has obviously been put to good use. Available to dealers shortly, the 250F has a phenomenal motor, killer suspension and solid handling to give it the ability to do it all.

“The 2006 KX250F truly is the best motocross bike Kawasaki has introduced to date,” said Kawasaki product development guy Karl Edmonson. “The engineers are on the gas. It’s cool to be at Kawasaki.”

I’d say he’s probably right.

Let us know what you think about the 2006 Kawasaki KX250F in the MCUSA Forum.


JC Hilderbrand

Off-Road Editor| Articles | Hilde is holding down the fort at MotoUSA’s Southern Oregon HQ. With world-class dirt bike and ATV trails just minutes away, the hardest part is getting him to focus on the keyboard. Two wheels or four, it doesn’t matter to our Off-Road Editor so long as it goes like hell in the dirt.

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