Words and Photos: Chris Worden

Kawasaki didn’t hold much back in 2009 when they revised their already stellar KX450F. It was at the beautiful Muddy Creek Raceway that we got our hands on it first, and we were quite impressed with the new EFI, frame revisions and excellent suspension. So what does Kawasaki do with an already impressive package for 2010? They continue to tweak and refine, as is the custom in the development of a top-level motocrosser. There are a number if important changes for 2010, most of which require a closer look to realize their presence.

Inside the motor is a new bridged-box (slipper style) piston. It shaves seven grams off the weight and has a 6mm-shorter skirt. They’ve offset the crankshafts reciprocating weight by 60% as well. The bike gets 40mm trimmed off the single-piece head/mid-pipe and the friction plates in the clutch get 75% more material. This is just the engine refinements!

The bodywork mounts to a chassis that features a new steering stem shaft with the goal of decreasing rigidity. The Kayaba fork keeps the DLC (Diamond-Like Carbon) coating and gets a different spring rate and revised damping to ease the initial stroke. The same goes for the rear end where the shock mounts to revised linkage ratios. Then there’s a new swingarm. Seat. And Bridgestones. Oh my!

It may look like last year’s bike, but there are some
pleasant surprises hidden between those green shrouds.

We packed up the new green beast and headed out to Milestone in Riverside, CA to put it through its paces. Accompanying me on this day was none other than WMA Pro Elizabeth Bash, who can typically seen aboard a Kawasaki KX250F, but ain’t skeered of a big 450.

In use, the bike feels like the KX450F we’ve come to know and love, only slightly easier to ride. Just like the rest of the 450 stable, it’s got a ton of power, but with a few ECU revisions it’s extremely easy to translate what you want from the bike, to the back tire. It wasn’t many laps into our test before Bash came off track and put the chassis refinements into perspective, “The chassis feels great. It rides a lot like my 250F. It dives into turns nicely and doesn’t feel too big. Can I keep it?”

Stock suspension always needs a bit of fine tuning, so we went to the clickers to find a better setting for what felt like a bit too soft of a ride. After a few additional clicks to the compression we were content. The revisions to the suspension and related components over the last two years has really smoothed out the back end. Now, exiting or entering turns with large bumps doesn’t beat up the rider as bad and the rear end tracks much better, translating more power to the ground when you need it most. Speaking of traction, the new Bridgestones are a welcome addition, though we couldn’t spin enough laps in one day to determine their tread life.

Overall we continue to be pleased with the quality of dirt bike Kawasaki is churning out. There was a slight bump in price for the 2010 model, ringing in at $8049 for the Lime Green model, a fair price for what may be the best bike in the big-bore category.

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