The 2010 fuel-injected Kawasaki KX450F proved both powerful and nimble.  [Ed. – Apologies for the brain malfunction yesterday . . . obviously Stewart rode a Yamaha to take the Supercross title last year.]   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.  The muffler is designed to keep noise levels down, while keeping power levels up.  At the same time, Kawasaki modified the shape of its bridged-box-bottom piston and recalibrated the ECU to provide a hotter and longer duration spark.

More positive shifting is said to come from a larger internal roller and stronger shift-spring tension. 

Damping settings are revised both in the front fork and in the rear shock absorber for 2011, and the new blue anodized damping adjuster caps add a touch of class.

Detail refinements include a new seat cover with side-surface texturing to better allow the rider to grip the machine, and even a new drive chain guide that is much more durable. 

On the track, we noticed that the engine and exhaust changes smoothed power delivery considerably.  There is really no hit, anywhere, which is  generally a good thing on a 450cc motocross bike if your name isn’t Carmichael or Stewart.  The power comes on strong from the low end, and builds to a solid mid-range.  The bike doesn’t scream on top, but there is useful over-rev, nonetheless.  Kawasaki took last year’s monster motor, and was able to spread and smooth power delivery.  The result is a machine that is less tiring, and hooks up better, while still providing all the acceleration you need to clear jumps and exit corners hard.  The exhaust note is distinctly quieter, at the same time.  Someone said “Speak softly, but carry a big stick!” and that is what the 2011 KX450F does. 

Our tester started out needing additional spring preload in the rear shock to compensate for his higher-than-targeted weight.  Handling felt very neutral after that.  The bike turns well, but doesn’t cut the inside line like many Suzukis do.  At the same time, the front end bites better than some of the slower-turning bikes out there.  A good compromise that our test rider was quite happy with.  Couple this turning ability with rock-solid straight line stability, and you have another Kawasaki motocrosser that handles very well right out of the box.

The transmission felt a bit notchy, but not overly so.  This could have easily been down to the fact that we were testing a brand new motorcycle.  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.

If we miss anything about two-strokes, it was how easy they were to start.  Despite being a four-stroke, the 2011 KX250F frequently starts on the first kick, and rarely requires more than two kicks. 

What stands out about the new KX450F is its motor.  Kawasaki has really taken out all of the peaks and valleys in the power delivery, delivering a bike that is fast, but controllable at the same time.  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. 

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