The KX450F's engine becomes even more rider friendly for 2010.
When it comes down to the sport of motocross there’s only one thing that counts: Winning. And the 2009 Kawasaki KX450F
(check out our 2009 Kawasaki KX450F First Ride
report to discover all of the changes) motocross motorcycle did just that in our 2009 450 Motocross Shootout
. In fact, this year’s KX was so good we assumed that Team Green would give it the BNG (Bold New Graphics) treatment for 2010 and call it a day. But with the competition continuing to evolve, in the form of hotly-anticipated bikes from Yamaha
, Kawasaki has tweaked its premium motocrosser all in an effort to make sure that green riders still come out on top.
For 2010 the KX’s essential platform returns, and although it’s nearly impossible to spot the individual changes, both the engine and chassis have been modified in order to deliver more performance around the racetrack.
Powering the KX is a 449cc 4-stroke Single that benefits from all the latest and greatest engine tuning tricks including liquid-cooling, double camshafts and fuel-injection, just like before. What’s new is the piston, cylinder, camshaft and crankshaft. For these components engineers turned to the racing department and utilized the same parts that they’ve been successfully running this year.
Perhaps the biggest change in terms of engine performance is the new piston. It’s both lighter and shorter for better performance through its 11,300 rpm-range (compression ratio remains the same). It slides inside a redesigned cylinder featuring tighter tolerances between it and the crankcase. The crankshaft is also new and makes use of a fresh design said to improve the engine’s tractability between the rear tire and the ground when you twist the grip. Lastly, a new camshaft was fitted and advances engine timing by 2-degrees.
The 2010 KX450F clutch set-up also gets some attention with a reengineered basket designed to not only enhance feel but operate cooler as well. The fiber friction plates were beefed up and contain more friction material which increases feel and durability. The same 5-speed transmission transfers power to the rear tire but it now does so with a slightly lighter chain.
With the electronic revolution, no hardware upgrades can be complete without software updates to match, so engineers reprogrammed the fuel and ignition settings in the ECU. Additionally, the rider or engine tuner has the ability to alter all the engine settings via an optional Kawasaki Fuel Injection Calibration Kit
. (We recommend checking out this device out as it has the ability to supply the biggest performance gain for the lowest cost of anything we’ve tried, all at the push of a button.)
A different exhaust header constructed out of stainless-steel replaces this year's titanium piece. It's a little over an inch-and-a-half shorter, and is claimed to boost mid-to-high rpm performance. Above the header sits two larger aluminum radiators. These now feature noticeably less-dense fin-core to help prevent debris from getting lodged in the radiators and causing potential damage. The units themselves are also stronger, allowing the reinforcement brackets to be done away with. Having previously raced several Kawasaki KX450Fs, our test rider Scott Simon said that the radiators were always prone to damage. Hopefully Kawi has rectified this problem with the new set-up.
In terms of the new chassis, the main frame’s steering head pipe has been tuned to reduce stiffness. At the other end, the swingarm employs a different internal cross section designed to further complement the bike’s overall rigidity balance. Also changed is the shock linkage, designed for improved rear wheel traction. Both the fork and rear shock absorber have slightly stiffer springs (0.48 kg/mm in the fork and 5.5 kg/mm on the shock) with updated valving to match. Lastly, the bike rolls on a different set of rubber in the form of Bridgestone’s M403 and 404-series intermediate terrain tires, said to give the bike improved traction on a wider variety of dirt.
To find out what this new bike was like to ride, Kawasaki hosted an introduction to the press at Pala Raceway in sunny Southern Cal. And if you dig long, mixed sandy/hard-packed tracks, and enjoy jumps that aren’t do-or-die, than Pala definitely might be your new favorite moto track.
Both the fork and shock spring rates have been increased slightly for 2010, but it was still too soft for our 175-lbs. pro test rider.
Just like before, getting the KX’s engine to fire is as easy as one or two kicks no matter the weather, elevation or if the engine is hot or cold. All motocross bikes should start this easy. If you’re a novice or even an intermediate level rider than it might be difficult to sense the differences, however, in the hands of our pro-level rider the new bike’s manners were noticeable.
Like before, you’ll be hard pressed to find a rider that thinks the Kawi needs more juice even in stock form. And it doesn’t matter what gear or rpm you operate the engine. Just twist the throttle and the KX rockets forward with the immediacy of a sportbike. Yet at the same time it generates power in such a linear, predictable fashion that it won’t catch you off guard or scare you, even if you’re new to the sport (again, the Kawasaki Fuel-Injection Calibration Kit
allows you to tune the bike’s engine to deliver power more or less aggressively based on your skill level and track conditions check it out, it’s the best money you’ll spend on your new KX).
“I think it’s a little bit faster than last year,” said Simon “It’s kind of deceiving, though. I think the ’09 bike’s power hit a lot harder. But on the new bike power comes on a bit more tame. It felt like you can get on the gas harder without having to worry about the bike ripping your arms out. It’s was way easier to control. Plus top end power is good and it revs forever.”
Given the copious amounts of instantaneous power, the need to work the clutch while riding isn’t as crucial as say on a 250F, thus it was difficult to tell if the clutch functioned any better than the old unit. But with the updates it would seem that it will offer increased durability for both the casual rider and racer alike.
One of the biggest differences between the ’09 bike and its replacement is the way it steers due in part to a new rear shock linkage and frame/swingarm rigidity updates.
In the morning while we were going through the stop-and-go photo runs, Simon had mentioned that the bike’s chassis felt essentially the same as before. But after he put in a solid moto, he quickly formed a new opinion:
“The chassis felt a lot better. It felt a lot more like a 250F in the sense that the back-end felt like it sat lower. It was way more comfortable to ride. The rear end tracked better and it wasn’t dancing around so much. On last year’s bike it had a tendency to stand up in the corner, but the year’s bike gets down into the corner much better.”
Simon, who weighs in right around 175 lbs, still complained about the suspension being too soft – as will any heavier rider who rips around at his pace.
“Suspension was really soft for me. But I think it was a little bit better than last year. It soaked up braking bumps well but on jumps it was bottoming a lot. They added some compression to it which helped. I also liked the way the rear end felt on the chop coming out of corners. Not only did it hook up and track really well but it didn’t beat me up too bad either. I definitely remember the ’09 bike not tracking as well as this new one.”
Despite the KX450F weighting 250 pounds with a fuel load of fuel, it actually feels quite nimble in the air as demonstrated by pro level rider Scott Simon.
Given the ample amount of traction available from Pala’s soft terrain surface, it was hard to tell if the Bridgestone tires were any better than the Dunlops on the ’09 bike, nonetheless they really did work well.
“The tires felt good, but probably any brand of tires would here,” joked Simon. ”The front pushed a little bit but it was probably the track more than anything. What I did notice though is the tires slid really well which helped in the flat corners.”
All said and done, the 2010 Kawasaki KX450F costs $500 more than its predecessor and should be rolling into your local Kawi dealer as you read this. Although the changes aren’t revolutionary and are pretty difficult to feel in the hands of your average motocross pilot; in the hands of our pro they made a difference. Most notable was the engine’s more friendly power delivery as well as its improved handling in the corners. So, if you’ve already got a ’09 bike in the garage is it worth making the upgrade to the ’10 model? If you’re serious about racing than it’s a no brainer.