For 2010, Kawasaki pumped up the spring rates on both ends. The fork went from a 4.6N/mm to a 4.7N/mm and the shock spring grew from a 52N/mm to a 54N/mm. The changes seem small on paper, but the performance is much different on the track. From two pro test riders and two vet-class intermediates ranging from 155 pounds to nearly 200, we all felt a similar harshness in the fork. I kept it secret from the second group of testers and the comments were identical.
We've had some luck backing out the compression damping (up to four clicks from stock) and opening up the rebound (two clicks at the most), but really the fork performance has been letting us down on the KX. The two areas that seem affected most are initial stroke on impacts from landings to choppy bumps, and what should be an upper mid-stroke valving setting on corner entries that doesn't allow it to settle completely. On landings and under impacts, the fork feels harsh and resistant to movement. It seems to not use the whole stroke and lacks progressiveness. On corner entries and down straights the front of the Kawi feels too light, twitchy even, and unsettled at best. The bike's front end rarely gave us a feeling of supreme confidence or connectivity with the track surface. This is even with the 2010 upgrade to Bridgestone's M403 front tire (which was one of our 2007 Products Of The Year based on its solid all-around performance). The fork tubes are up in the triple clamp to the limit of the guide lines. We even tried running 95 to 98mm of sag and didn't have much luck with it either settling the front end down or making the harshness go away. So what's next? We're testing more settings and spring rates to dial it in.
The shock performance is great at 100mm of sag. Not 102mm. Exactly 100mm. Here it is tractable, plush and resistant to harsh bottoming. At 102mm the shock still feels fine but the front end gets a lot worse. The rear of the bike doesn't kick or do anything out of the ordinary, and we're leaving the clickers alone out back. The bike's balance is very picky to say the least. We commented on an unbalanced ride in the past on the KX450F with inconsistent front-end handling being prominent, and it's always been imperative to double-check sag settings when things get out of whack. But so far, we're having more trouble dialing in a good setting than before.
There are chassis changes for 2010 that could be affecting this other than the spring upgrade. The steering stem shaft is reduced in diameter to increase flex for lighter handling, and the swingarm drops some rigidity as well. These could be and likely are contributing to our front-end woes, and hopefully as we continue to test we'll locate and remedy our fork complaints. Also, it's important to note we're just now approaching the 10-hour mark on this ride and the suspension components should only free-up from here. The interesting thing is that with all this twitching in the front end the bike still rides very stable at high speed. Just like in years past, the bike feels long and low and planted on fast straights but slowly deteriorates as you set up and slow for a corner, and continues while accelerating out of the turn. At speed, the ride is fine.
2010 Kawasaki KX450F
MSRP: $8049
Weight (tank empty): 240 lb
Seat height: 37.2 in.
Seat-to-footpeg distance: 21.1 in.
What's Hot!
Amazing throttle response no matter the rpm
Incredible pull throughout the rpm range
Decent exhaust note is a huge improvement over 2009
Starts easily
Stable at speed
Sweet showroom shine
What's Not!
That sweet showroom shine scratches easily
Give us some balance
Kris Keefer
5'11"/160 lb/Pro
Once on the 2010 KX450 I noticed that the muffler sounds a little better this year, which is very nice! On the track the bike has great smooth roll-on power, but once you're coming out of a corner in second gear getting ready to shift to third hold on 'cause it takes off. Mid to top-end power is plentiful, and you will not be asking for more.
On the handling side I could not get along with the fork at all. The fork felt harsh everywhere. I tried a lot of different settings but just was not happy with it. Coming out of corners on small acceleration chop the fork danced around and was twitchy. On big slap-down hard landings the fork seemed like it didn't want to use the whole stroke. You can especially feel it coming into corners where you find braking bumps. The bike feels unbalanced on the suspension side. The shock feels like it works well and soaks up big hits with ease, so with some more suspension tuning we will see what this bike has to offer against the other new bikes coming out.
Ryan Orr
5'9"/165 lb/Pro
My first impression of the twenty-ten KX450 is that it's basically a rocket strapped to a rolling chassis. The motor has that same great EFI response, strong mid and great pull up top as the '09 model. The bike pulls in any gear whether you're over revving it or lugging the crap out of it.
The handling was almost on par with last year's bike. It just took some fine-tuning to get the bike settled in. The spring rates are a little firmer for 2010, and I think the '09 spring rates worked best for my weight and riding style. The bike has that same great straight-line stability as well as the steering-the-bike-with-the-rear-end characteristic as last year. Coming out of corners I could pick a point and go as well as change my line easily if there was an unexpected obstacle. The bike also feels light and easy to flick around in the air.
The new KX450 is a great all-around MXer but needs a bit of setup to work right. Can't wait to test it back-to-back with the rest of the 450s!