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2014 Kawasaki KX250F Project Bike

Thursday, May 22, 2014


Even though Yamaha stole the show in the production 250 class this season we’re still big fans of Kawasaki’s tried-and-true KX250F motocrosser ($7599). With its more traditional-feeling chassis and ferocious, hard-hitting powerband the Green machine is still our favorite for throwing up roost at the track, and on narrow single track trails.

Perhaps the best attribute of the little KX is its versatility. Whereas some SoCal moto tracks like Glen Helen and Racetown 395 favor the immediate thrust of a 450, the KX250F has so much acceleration that it holds its own at these faster, more wide open-style tracks. Conversely, on tighter circuits like Milestone, the twin fuel injector-equipped engine has enough mid-range punch to pull third gear through inside ruts—a big help when trying to boost off a tricky jump, right out of a turn.
The KX250Fs SFF fork is very sensitive to preload adjustment. Heavier riders will need to add preload however fork action does get harsh near its maximum setting.
The KX250F has excellent suspension settings out of the box. We especially love the taut feel of the shock.
After our OE-fitted MX51 was worn out we spooned on a wider 110-series MX52 intermediate-to-hard-pack tire. The tire not only offers great grip on a wide range of terrain its plenty durable  too.
(Top) The KX250F’s SFF fork is very sensitive to preload adjustment. Heavier riders will need to add preload however fork action does get harsh near its maximum setting. (Center) The KX250F has excellent suspension settings out of the box. We especially love the taut feel of the shock.(Bottom) After our OE-fitted MX51 was worn out we spooned on a wider 110-series MX52 intermediate-to-hard-pack tire. The tire not only offers great grip on a wide range of terrain it’s plenty durable, too.

The rider can also easily tune the engine’s powerband by swapping between one of three power couplers. The ‘white’ plug is ideal for deeply tilled earth and power-sucking sand, or if you want an aggressive power hit. Conversely, the ‘black’ coupler aids rear wheel traction on slick hard-pack terrain by smoothening the powerband and making the engine feel more tractable, similar to adding a heavier flywheel. Overall, we preferred the standard ‘green’ plug. Another neat feature is launch control aimed at helping less experienced riders obtain better starts during a race. But since we didn’t participate in any local competitions, we can’t comment on how it performs.

Kawasaki was one of the first brands to make the switch from a conventional twin-spring equipped dual-chamber fork to the newer-style Separate Function Fork by Showa. And while its first go at it (2011) delivered an unnatural feel, we’re happy to report that the latest version is almost spot-on.

The KX benefits from very well-calibrated suspension settings out of the crate that function for a broad range of rider weights and speed-levels. If you’re a faster, or heavier rider (over 170 pounds) the fork feels under-sprung in certain conditions. Adding preload to the fork spring helps alleviate the condition by allowing it to operate at a favorable stroke angle but it does make for a harsher feel as you near the upper spectrum of adjustment. Though, if you ride primarily at smaller, smooth tracks, or single track off-road, it performs especially well, diving in smoothly through sharp turns and around obstacles. The shock is more adept at fast riding yet still gives a nice planted feel when squatted with the throttle. When the rear tire is fresh it also hooks up very well.

Speaking of traction, since the knobs on our OE-fitted Dunlop rubber were beginning to dull we replaced them at the 14-hour mark with Big D’s recently released Geomax MX52 knobs. Developed over the last couple seasons in pro Supercross and outdoor motocross competition, the MX52 replaces the MX51 and offers a wider operating range on intermediate-to-hard pack dirt. Considering how much muscle the KX250F has in stock form, we mounted a larger 110-section rear tire for added grip and a bigger footprint at lean. Up front we stuck with the stock 80/100 series hoops.
We’ve clocked almost another 14 hours on the tires with some pleasing results. Not only do they grip in a variety of terrain, we’ve experienced favorable wear characteristics, too. While they surely show signs of wear they still perform well during weekend play rides at all sorts of tracks including Racetown’s slick hard pack and Milestone’s deeper morning loam. We even got a chance to climb over trees and through deep mud and snow during an early season spring trail ride.
KX250F Settings
Engine
Map: Green (stock)
Hours: 28.3
Suspension
Fork
Preload: 28 (turns in)
Compression: 8 (turns out)
Rebound: 11
Shock
Sag: 103mm
L/S Compression: 9 
H/S Compression: 1.5
Rebound: 10


Keeping the engine serviced is key if you want it to feel ‘fresh’ during the course of a season. While the owner’s manual recommends changing the oil and filter at 15-hour intervals, we prefer to drop the fluid after five hours of runtime. This reduces the chance of the clutch contaminating the oil and vice versa, and helps keep the engine feel new and tight. We’ve always had good luck with Maxima’s Maxum4 synthetic blend oil. We run the standard 10W-40 viscosity but if you ride in really hot weather (over 104 degrees Fahrenheit) it’s a good idea to bump to a thicker blend.

On a 250F, you need all the power you can get. So it’s important to keep tabs on the air filter’s condition. If you ride on moist tracks, the filter stays clean. But if you ride where it’s dusty, you can easily clog it after a few motos. Rather than
For 2014  Kawasaki has ditched its rock hard grips for a softer set-up that is no longer vulcanized to the controls. This makes it much easier to remove and replace.
While we like the softer-for-2014 hand grips  they do wear faster. We replaced them with a set of Kevlar Dual-Compounds from Renthal.
(Top) For 2014, Kawasaki has ditched its rock hard grips for a softer set-up that is no longer vulcanized to the controls. This makes it much easier to remove and replace. (Below) While we like the softer-for-2014 hand grips, they do wear faster. We replaced them with a set of Kevlar Dual-Compounds from Renthal.
replacing it, we rely on Maxima’s can-based Air Filter Cleaner which easily removes dirt with minimal elbow grease. After rinsing it a few times in warm water we let it dry overnight before dousing it lightly with FAB-1 Spray-On Filter Treatment.

Although we love the new softer style OE-grips they wear out much faster than the tougher pre-2014 grips. So we sliced them off (the grips are no longer vulcanized to the handlebar and are now much easier to remove) and replaced them with a set of our favorite Kevlar Dual-Compound set-up from Renthal. The dual-compounds offer the best of both words: feeling squishy to the touch, yet offering fantastic durability and resistance to wear. They also happen to be the same set-up Supercross champ Ryan Villopoto runs on his practice and race bikes. In an effort to keep the grips from shifting during motos it’s a good idea to use both grip glue and three strips of safety wire.

After 28 hours of run time, the stock chain is fully stretched and in dire need of replacement. While we’re at it we’re going to match it to a fresh pair of sprockets. Though, we’re not particularly hard on clutches, ours is showing signs of wear which is making the bike feel slower off of turns. The orange launch control light (also serves as a check engine indicator) has also illuminated so we need to dissect that issue as well. Stay tuned…

2014 Kawasaki KX250F Project Photos
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Comments
motousa_adam   May 22, 2014 10:47 AM
Yup, it's pretty crazy. But you have to remember that these motorcycles are essentially race bikes off the showroom floor. You ride them pretty much full throttle everywhere. And since they are ridden in the dirt, sand and mud they are subjected to conditions that street bikes aren't-- hence why everything wears out so fast... Adam
neo1piv014   May 22, 2014 09:47 AM
I find it kind of insane how quickly these MX bikes need maintenance. I was reading the owner's manual on a friend's bike and it was talking about replacing the piston every 500 miles. I guess they lead a very rough life, but I can't begin to fathom replacing a chain after 24 hours run time or a piston before you even hit the break in mark on most other bikes. Then again, I guess that's how you get so much power out of such a small machine.