2009 Kawasaki KX450F/KX250F 1st Look

June 17, 2008
JC Hilderbrand
JC Hilderbrand
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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.

2009 Kawasaki KX450F
The big news for 2009 so far has been the addition of another EFI-equipped motocrosser, Kawasaki’s potent KX450F.

Those guys in yellow scooped ’em all, but the rest of the motocross world wasn’t long to catch on with the whole fuel injection thing. Kawasaki revealed its 2009 KX450F and this bad mama-jama has joined the 12-hole revolution! Much like the Suzuki system, the new EFI doesn’t require a battery to run the pump. Using the kickstarter to generate electrical charge, the system is fed current to the ECU, then the aluminum in-tank fuel pump and finally the injector, all in a single stroke of the lever. The injector is set at a 45-degree angle which is said to emphasize midrange power. A 43mm Keihin throttle body ultimately distributes the goods into the 12.5:1 (up from 12.0:1) compression ratio inside the cylinder.

A redesigned fuel tank still holds 1.8 gallons despite having the internal pump. The pump itself is wrapped with a rubber fuel filter cover which traps fuel and retains a stable supply of gasoline during riding.

Shortening the cylinder head by 5mm, reshaping and lightening the crankshaft, revising intake and exhaust ports and reshaping the piston highlight the motor mods. The exhaust pipe is now a one-piece titanium unit which is claimed to meet “future noise regulations.” Hopefully that means it won’t be as raspy and obnoxious as the 2008 model, though some riders liked the sound.

The chassis has been modified with a sharper rake (26.7 vs 27.1 degrees) and the fork offset is down to 23mm from the ’08’s 24mm, which should be evident in the handling of the machine. We didn’t find the KX-F particularly sluggish last year, but it wasn’t the sharpest handling bike in our shootout. Dropping a claimed 1.8 pounds from the aluminum frame will help as well. The cross sections of the main spars were shrunk, now 2mm shorter and 3mm thinner, the head pipe was trimmed and the subframe is narrower.

2009 Kawasaki KX450F
A new fuel tank houses the aluminum fuel pump and 1.8 gallons of gas. Capacity has been an issue with the EFI machines, with Suzuki only fitting 1.6 gallons.

On the back end, the new tapered swingarm mounts 3mm higher and is claimed to be nearly a half-pound lighter. A new linkage mount increases the suspension stroke of the 50mm piston Kayaba shock (boosted from 46mm). Both suspension components offer 12.4-inches of travel and full adjustability, as always. The Kayaba fork gets the ultra-cool Diamond-Like Coating, but of a new variety which is said to offer 15 percent less stiction.

One-piece radiator shrouds are supposedly slimmer this year and the seat uses firmer urethane and a gripper seat cover for better control. When the rider isn’t sitting down they’ll appreciate the 50mm wide footpegs. Not only do the pegs add traction, but they add to the beefier look, as does a set of black alumite-coated rims. To keep with the dark look, the magnesium coloring on the triple clamps and engine covers has been traded out for black.

2009 Kawasaki KX450F Specifications

Engine: Liquid-cooled, four-stroke single with DOHC and four valve cylinder head
Displacement: 449cc
Bore x stroke: 96.0 x 62.1mm
Compression ratio: 12.5:1
Fuel Injection: 43mm Keihin Throttle body
Ignition: Digital DC-CDI
Transmission: Five-speed
Rake / trail: 26.7 degrees / 4.6 in.
Front suspension / wheel travel: 48mm inverted, Kayaba AOS with DLC coated sliders, 22-position compression and 20-position rebound dampening adjustment / 12.4 in.

2009 Kawasaki KX450F
The Kayaba fork gets a new variety of Diamond-Like Coating which is said to offer 15 percent less stiction

Rear suspension / wheel travel: UNI-TRAKr linkage system and Kayaba shock with 22-position low-speed and stepless high-speed compression dampening, 22-position rebound dampening and fully adjustable spring preload / 12.4 in.
Front tire: 90/100-21
Rear tire: 120/80-19
Front brake: Single semi-floating 250mm petal disc with dual piston caliper
Rear brake: Single 240mm petal disc with single-piston caliper
Overall length: 86.0 in.
Overall width: 32.3 in.
Overall height: 50.4 in.
Wheelbase: 58.3 in.
Ground clearance: 13.4 in.
Seat height: 38.0 in.
Curb weight: 247.1 lbs.
Fuel capacity: 1.8 gal.
Color: Lime Green
2009 Kawasaki KX250F

A new aluminum chassis is the big news on the quarter-liter. By reshaping the main spars and using less total pieces, engineers claim to have dropped 2.2 pounds and increased rigidity balance throughout. The swingarm pivot is higher and lighter for 2009 and the D-shaped unit also accepts a 50mm piston shock, though the 250F is still using Showa components. From a distance they look like the same DLC-treated lower tubes as the 450 has, but the 47mm Showa fork has titanium-coated inner tubes instead. The fork has 1mm-less offset.

In the motor, though engine oil capacity was dropped by 0.2 quart as a weight-savings ploy, a KX450F oil filter has been installed to help keep things clean. The intake port has been redesigned for better flow of fuel/air mixture on the way in while a tapered titanium exhaust spits them out. Also dealing with the motor is a more efficient cooling system, spearheaded by 6.4mm wider Denso radiators with redesigned four-fin louvers. The cylinder head water jacket has a revised route for improved cooling in the high-revving, 13.2:1 compression ratio engine. Like its big brother, the 250F gets a new seat cover, graphics and black brake guards. We praised Kawi for putting black backgrounds on its 250F in 2008 and the engineers have done even better this year by simply making them out of black plastic, something budget racers will certainly appreciate.

2009 Kawasaki KX250F
The 2009 KX250F doesn’t have quite the earth-shattering changes as its big brother, but new bodywork and minor engine changes accent a 2.2-pound lighter chassis.

2009 Kawasaki KX250F Specifications

Engine: Four-stroke single with DOHC and four valves
Displacement: 249cc
Bore x stroke: 77.0 x 53.6mm
Cooling: Liquid
Carburetion: Keihin FCR37 and hot start circuit
Compression ratio: 13.2:1
Ignition: Digital CDI with K-TRIC throttle position sensor
Transmission: Five-speed with wet multi-disc manual clutch
Final drive: Chain
Frame: Aluminum perimeter
Rake / trail: 27.7 degrees / 4.8 in.
Front suspension / wheel travel: 47mm inverted Showa twin-chamber telescopic fork with 16-way compression and rebound damping / 12.4 in.
Rear suspension / wheel travel: UNI-TRAKr linkage system and Showa shock with 13-way low-speed and stepless high-speed compression damping, 17-way rebound damping and fully adjustable spring preload / 12.2 in.
Front tire: 80/100-21

2009 Kawasaki KX250F
Not only is the shape different, but the new sidepanels are made of black plastic instead of white with black background stickers. The front panel is the same.

Rear tire: 100/90-19
Front brake: Single semi-floating 250mm petal disc with dual piston caliper
Rear brake: Single 240mm petal disc with single-piston caliper
Overall length: 85.4 in.
Overall width: 32.3 in.
Overall height: 50.0 in.
Wheelbase: 57.9 in.
Ground clearance: 13.4 in.
Seat height: 37.6 in.
Curb weight: 229.9 lbs.
Fuel capacity: 2.1 gal.
Color: Lime Green

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