The 2011 Kawasaki KX450F Digital Fuel Injection (DFI) automatically adjusts to suit track and climate conditions, and offers stable fuel metering even when landing from jumps in tough motocross conditions.
The DFI system includes a compact and lightweight ECU, a 43mm throttle body, a lightweight aluminum fuel pump and an ultra-fine atomizing injector. Set at a 45-degree angle for ideal mid-range power, the 10-hole injector sprays precise, 60-micron fuel particles for smooth power delivery and accurate engine response throughout the rpm range.
Add choppy suspension to the jumpy power and you had a potentially great machine that missed the mark slightly. As a result, the 2011 Kawasaki KX450F felt big and clumsy in the face of the new nimble class warriors like the Honda CRF450R and the Yamaha YZ450F.
It started with the heart of the engine with a new piston, a larger volume muffler, ECU changes and a shift mechanism upgraded with a larger internal roller and more shift spring tension. Chassis upgrades are limited to stamped steel head-stay plates that replace machined aluminum parts. As far as rider accommodations go, the seat foam is a bit firmer for longevity and the seat cover have improved traction on the sides.
Despite the small list of changes the KX has undergone a profound personality alteration. The clutch pull is light for the class, and the shifting is quiet and smooth but solid. It is calmer and lets the rider spend more brain and muscle power dealing with the track by the bike demanding less attention to control traction.
When you ride both bikes in the same conditions you instantly realize what a profound improvement the relatively minor changes have produced. The new bike is still a missile, but initial throttle control is far less critical and demanding. Racetown has some a fast straight with big rollers, and the suspension has the control to keep the bike calm and planted there. Sections that previously required exceptional throttle control now let the rider relax. Tracking through high-speed rough is built right into this chassis, but now the suspension has joined the party.
The 2010 fuel-injected Kawasaki KX450F proved both powerful and nimble. Kawasaki has moved on with a re-designed 2011 KX450F that includes engine tweaks, revised suspension settings, improved shifting performance and even a revised seat cover.
New noise regulations require production motocross bikes to come in at 94db, or less, and Kawasaki accomplished this with a higher-volume muffler for 2011. More positive shifting is said to come from a larger internal roller and stronger shift-spring tension.
On the track, we noticed that the engine and exhaust changes smoothed power delivery considerably. Kawasaki took last year’s monster motor, and was able to spread and smooth power delivery. The exhaust note is distinctly quieter, at the same time. Handling felt very neutral after that. The bike turns well, but doesn’t cut the inside line like many Suzukis do. Shifting performance was nevertheless positive, and we never missed a shift.
Brakes were strong and controllable, right there with the brakes on the Honda our test rider normally races. The ergonomics on the Kawasaki are a bit roomier than most of the competition, and our relatively tall (6′2″) test rider appreciated them.
The handling is neutral and predictable, and the revised suspension is balanced and well damped. The 2011 Kawasaki KX450F carries a U.S. MSRP of $8,149. For additional details and specifications, visit Kawasaki’s web site here.