2009 Kawasaki KX250F First Ride

Steve Atlas | September 10, 2008

2009 Kawasaki KX250F
Kawasaki has come out swinging with the totally new 2009 Kawasaki KX250F. Pro test rider Matty Armstrong demonstrates its mid-air “stability.”

Motocross bikes are judged solely on performance, plain and simple. Unlike street-going motorcycles, where things such as comfort and wind protection are important, MXers are all about one thing: getting around the racetrack fast. It’s all about speed and how easily attainable that speed is. For this reason, the big four Japanese manufacturers come out with updated or new machines what seems like every year these days. Thus it is no surprise that for 2009 the Kawasaki KX250F is all-new from the ground up. And it’s good – really good.

Motorcycle-USA.com got a chance to swing a leg over the new green machine at Piru MX Park in Santa Clarita, California to see what the new quarter-liter four-stroke is capable of. Handling the testing duties were Associate Editor Adam Waheed and I on the staff side of things, while former pro Motocross and Supercross rider Matty Armstrong joined in to throw down some fast lap times and big whips, just how we like it.

“The engine is so responsive, it’s spot-on,” said fast-guy Armstrong, after getting off the Kawasaki for the first time. “It has to be the best running carbureted bike I have ever ridden. Twist the throttle and it instantly comes to life. It does taper off ever so slightly at the top, but it’s barely noticeable.”

“You can’t help but notice the new motor right away. This is by far the best Kawasaki 250F engine to date, maybe the best 250F engine of them all,” agreed Waheed, who at a somewhat slower pace noticed absolutely nothing wrong with the KX engine. “Most of the time you need to rev a 250F pretty high to get it going, but the KX starts pulling instantly off idle with extremely precise throttle response, feeling almost is if its fuel-injected. And it runs good all the way though the rev range.”

This “spot-on” power delivery is the result of an updated 249cc four-stroke powerplant. The new lump features a redesigned cylinder head with a new intake port design that is said to be smoother, thus freer flowing, as well as being better sealed so as to limit power loss from leakage. New titanium valves now have a longer service life, while the crankshaft has a so called “factory-level” balance. The improved balance is a result of a revised crank web that is said to reduce engine vibration, smooth out the power delivery and improve throttle response in the low- to mid-range. A new tapered titanium exhaust pipe rounds out the new 249cc liquid-cooled engine.

Keeping the updated engine running at the proper temperature is a new, six-percent larger radiator that features different water jacket routing for more effective flow and redesigned louvers. Increased from three to four blades, the new louvers are smaller with a shallower angle to increase the flow of air.

An updated chassis and revised suspension have made for one of the lightest feeling 250cc four-strokes on the market. The Kawasaki’s handling was universally loved.
An updated chassis and revised suspension have made for one of the lightest feeling 250cc four-strokes on the market. The Kawasaki’s handling was universally loved.

Less engine oil is used to reduce weight and mechanical loss, while a crankcase pump oil filter pulled off the KX450F is employed for easier maintenance. To cope with the added ponies is a more durable transmission – the result of stronger gears that are more spaced out. Clutch and generator covers are also strengthened for improved durability. Aimed at improving shifting and clutch feel, Kawasaki switched to a new ratchet drive shift mechanism and integrated the clutch cable holder into the crankcase. Also changed to improve shifting feel were the lever ratios, shift spring rates and shaft locations.

“It’s noticeably thinner between my legs,” Armstrong added. “The chassis feels really good and handles great. It turns right where you want it to and the suspension is the best yet. In the middle of the corner the suspension rides right in the travel where it needs to be and it’s equally good off jumps – no funny kicks or anything unpredictable. Bump absorption on- and off-throttle is just as good as well.”

To attain that slimmer feel, Kawasaki redesigned the aluminum perimeter frame and sub-frame, blending forged, extruded and cast parts. As a result, the new frame now features fewer parts and gussets, thus weighing in 2.2 lbs less than the ’08 model. Reshaped main frame spars provide a 6mm narrower overall profile at the rider’s knees. A new manufacturing process and down tube design shed weight from the frame and combine with relocated engine mounts to improve rigidity and balance. This is said to equate to “enhanced stability with a better rigidity balance and improved drive from the rear tire.”

“It definitely feels smaller than last year’s bike,” Waheed said. “The overall feeling from the KX is noticeably lighter than last year, making it more flickable and easier to put it where you want it. I couldn’t help but to instantly like KX, it inspired loads of confidence right from the word go.”

Mated to the redesigned frame is a new swingarm, which now pivots from a higher position on the frame. The unit is lighter, features a new, more tapered design with a “D” profile and a new cross bracket. To achieve a longer suspension stroke, and thus more precise rear suspension tuning, the Uni-Trak link is now mounted below the swingarm. Controlling the new swingarm is an updated Showa shock, which now uses a larger 50mm internal piston diameter with revised damping characteristics.

“The suspension action is really smooth, no weird kicks or anything unpredictable whatsoever,” remarked Waheed.

A first for a Lites-class OE machine are new Showa forks with titanium coated inner tubes. The black-like coating decreases stiction while providing a super-hard surface to aid in preventing scratches and damage to the tubes in the never-ending search to keep fork seals from leaking. To achieve the “optimized rigidity balance” the outer fork tubes have decreased rigidity, while a new black upper triple-clamp has been reshaped and stiffened. Fork off-set is 1mm less and new wrap-around fork guards round out the updates.

More cooling fins and a bigger radiator keep the more powerful engine running cool.
More cooling fins and a bigger radiator keep the more powerful engine running cool.

To increase durability, a larger resin skid plate and longer lasting chain guide are now used. For improved styling, and ease-of-use, new dual-injection-molded, two-tone black and green plastic shrouds and side number plates are used, a process which was first seen on Honda’s CRF250 last year. This means hassling with number plate backgrounds is a thing of the past. The updated bodywork was also designed with ergonomics in mind, and combined with a new, slimmer seat, makes for a smaller interface between the rider’s legs. Rounding out the KX updates are wider 50mm footpegs that allow the rider more stability and freedom of movement.

“Really, the only complaint I had was the handlebars are too low for a 6-foot tall dude like myself, though that is easily fixable. But overall, I would have to say it’s one of the best, if not the best 250cc four-stroke I have ridden so far.” Waheed concluded.

Without hesitation, Armstrong summed things up simply and to the point: “This is the best 250F I’ve ever ridden, bar none!”

Better handling? Check. Improved suspension action? Check. Smaller feeling? Check. More bottom-end? Check. All this compared to the ’08 KX250F, which in our eyes was already one of the best 250s on the market. Thus it begs the question: Is the ’09 Kawasaki KX250F the best quarter-liter four-stroke motocrosser of them all? Stay tuned for our upcoming 250F shootout to find out.

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Steve Atlas

Contributing Editor |Articles | Professional-grade speed and an attitude to match, Steve Atlas has AMA racing creds that are even more extensive than his driving record.