Comprehensively re-designed with a new fuel-injected engine, chassis, bodywork and extensive durability enhancements, the 2009 Kawasaki KX450F motocrosser is sleeker, faster and more high-tech than ever. Although it has undergone the biggest makeover since its original 2006 debut, the new KX450F still shares a clear bloodline with its championship-winning predecessors.

A leaner, stronger and EFI equipped racing thoroughbred

Comprehensively re-designed with a new fuel-injected engine, chassis, bodywork and extensive durability enhancements, the 2009 Kawasaki KX™450F motocrosser is sleeker, faster and more high-tech than ever. Although it has undergone the biggest makeover since its original 2006 debut, the new KX450F still shares a clear bloodline with its championship-winning predecessors. 

The upgrade to Electronic Fuel Injection (EFI) eliminates the need to adjust engine settings to suit track and climate conditions and offers stable fuel-metering even in tough motocross conditions –without sacrificing the hard-hitting character of its predecessor. The new EFI system includes a compact lightweight ECU, a 43mm throttle body, a newly designed lightweight aluminum in-tank fuel pump and an ultra-fine atomizing injector. Set at a 45° angle for ideal mid-range power, the 12-hole injector sprays precise 60 micron fuel particles for smooth power delivery and improved engine response at partial throttle.

Designed specifically for motocross, the KX450F’s lightweight EFI system doesn’t require a battery –the engine can be started within three rotations of the crankshaft, using only the electricity generated through the kickstarter. Kawasaki engineers achieved single-kick start capability by having the ECU power-up at the initial movement of the kickstarter. The system delivers electricity in the following order: ECU, fuel pump, and then injector.
 
The EFI system’s increased electrical needs are handled by a new larger AC generator rotor that also increases the engine’s rotational inertia. A reshaped and lighter crankshaft, with its rotational inertia unchanged, balances out the bigger ACG rotor. A wedge-shaped crank web increases the offsetting moment to help achieve a crankshaft balance factor of close to 60 percent. This is on par with Kawasaki’s factory racers. The end result of these changes is reduced engine vibration, smoother power delivery and a noticeable improvement in low rpm throttle response.

The new engine is more compact and lighter, with a 5mm shorter cylinder head that also features revised intake and exhaust ports for improved engine performance through the entire rpm range. A new piston with a reshaped top surface raises the engine’s compression ratio from 12.0 to 12.5:1 and works in conjunction with a new one-piece titanium exhaust pipe to provide improved low-mid range performance. Rounding out the powertrain enhancements is a larger-volume silencer body that’s able to meet future noise regulations. It uses long-fiber packing that lasts longer and extends service intervals.

Overall, the new KX450F’s ample power is delivered in a smoother, more user-friendly manner with a linear low-rpm throttle response and torque delivery that reduces fatigue and allows riders to go faster for more laps.

Design of the aluminum frame, suspension components and settings was focused on translating this broad powerband and responsive throttle into better drive off the corners. Other goals of the ’09 revisions were lighter handling and a slimmer chassis with an optimized rigidity balance. To achieve these aims, every part was examined or revised. The cross-sections of the main spars were shrunk, the head pipe is slimmer and a new process was used to form the down tube, while the reshaped sub-frame is narrower yet stronger.

A blend of forged, extruded and cast parts, the revised chassis dimensions, parts reduction and gussets of the new frame equal a 1.8 pounds weight savings and an increase in stability and traction, thanks to improved rigidity balance.
 
Working in conjunction with the frame revisions is a new aluminum swingarm now pivoting from a 3mm higher position on the frame. The swingarm features a more tapered design with a “D” profile and new cross bracket. A longer rear suspension stroke, and thus more precise rear suspension tuning, was achieved by mounting the arm of the Uni-Trak® rear suspension linkage below the swingarm.

Complementing the chassis balance with settings optimized for experienced racers, the KX450F’s suspension offers a host of new features for better cornering and sharper handling. The Kayaba Air-Oil-Separate (AOS) fork has a new Diamond-Like Carbon (DLC) coating on the outer surface of the inner fork tubes which offers a 15 percent reduction in stiction when the fork is exposed to lateral forces that hamper slide action. The result is improved fork response, especially during cornering. The overall suspension action is even smoother due to the friction-reducing Kashima Coat treatment on the inside surfaces of the outer fork tubes and the rear shock reservoir.

Increasing the rigidity in the reshaped upper triple clamp and decreasing it in the new outer fork tubes optimized the rigidity balance of the front end. Adjusting the race-oriented suspension settings and reducing the fork offset from 24 to 23mm further enhanced the new KX450F’s lighter handling and increased its front wheel traction. Enlarged, wrap around black fork tube guards provide greater protection for the inner tubes.

Matching the smooth action of the fork, the Kayaba rear shock received a new body design and a larger 50 mm piston (previously 46 mm). Its improved response, damping and bottoming performance equate to a better ride and increased maneuvering precision. It also features a Kashima Coat treatment on the shock internals. Its easily accessible dual compression adjustability - allowing high-speed and low-speed damping to be tuned separately - gives mechanics and riders the ability to fine-tune for difficult track conditions.

Durability enhancements are not limited to internal components on the new KX450F. The larger, resin skid plate and narrower, longer lasting chain guide both offer better protection without increased weight and are examples of the race-oriented durability improvements that abound on the new KX450F.

In addition to giving the ’09 KX450F a stunning new look, the bodywork was completely revised with the main focus on rider comfort and ergonomics. Offering the rider an even slimmer interface with a natural positioning makes it easier for racers to relax and go fast. Included in the sleek new bodywork styling are one-piece dual injected, two-tone green and white plastic shrouds and side number plates.  This new bodywork translates into less time hassling with backgrounds and graphics and more time collecting trophies.

A slimmer new seat design with firmer urethane, a non-slip top surface and smooth sides provides good seated grip and excellent rider mobility. The frame echoes the slim profile at the top, but widens at the lower end by the ankles to provide the rider with better feel and control. Completing the rider interface improvements are wider 50mm footpegs that offer increased grip and a more comfortable platform.

The 2009 KX450F will be available in Kawasaki Lime Green, with black alumite-coated rims and aggressive graphics for a factory appearance.

Racers who ride their KX450F at designated events are eligible to receive support from Team Green™, Kawasaki’s amateur racing support program. Each year, Team Green provides regional support vehicles and highly trained technicians at more than 100 events, offering technical information and assistance to those who race Kawasaki products. Kawasaki also offers a comprehensive contingency program for amateur and professional riders who place well at designated events.