2010 Kawasaki KX450F – Dirt Rider Magazine

www.palaraceway.com). This track is new in SoCal and incorporates a good mix of terrain for a first test. We also took it to our long-standing testing grounds; Racetown 395 (www.racetown395.com) and the playful Piru MX Park (www.pirumx.com).Honestly, there simply isn’t a bike to compare Kawasaki’s power prowess to in the 450 motocross class. The motor’s pull from just off bottom to warp speed will blow your mind, and if that’s what you buy a dirt bike for, then by all means sign up at your Kawasaki dealer for a 2010-you’ll be winning parking-lot shootouts all day long. You might want to hold on for a little bit, though. We haven’t ridden any other 450s from 2010 yet. Maybe they’re all this fast (not likely).Kawasaki’s 450 from 2009 had plenty of punch for all of us but apparently not enough for Kawasaki engineers. They updated, improved and redesigned parts from the piston to the exhaust system. Thankfully, this one has a muffler that isn’t disposable like the obnoxious 2009 version. It’s still barky and loud, but at least it’s clean sounding. The top end also sees tweaks to the cam timing. On their way to the bottom end, Kawasaki concentrated on weighting and balancing the crank to modify power delivery and response. They did some clutch work and slapped some big, beefy radiators on this girl to keep her cool. The nerd-department even got to play with revised ECU settings. If you want to get into deep, deep detail, check out www.dirtrider.com for the inside story on all the new parts and updates on the KX450F. But here, let’s talk about how it works!If you need to understand one thing about this bike, it’s this: Hold on. Seriously. Hold on. You might be distracted with how easily it starts and how clean the response is. Heck, you might even be fooled by its great bottom-end roll-on and smooth delivery just up to the lower midrange that this bike is EFI-mellow. But just as this calm princess creeps into high-rpm second gear (or low-rpm third, depending on your preference for revs) she explodes into a hellish roar of fire and fury! The bike bolts forward with incredible acceleration. If you’re man enough to shift up, it will repeat the performance until both of you incinerate from the surrounding air’s friction or travel back in time.The bottom one-third of power doesn’t hit so aggressively as to spin you out-although it does pack a decent wallop-so it’s usable on corner exits and/or slippery flat turns. But make sure you’re pointing in a safe direction when you open up the go-nozzle further.In all, this makes for a very versatile engine platform. You can ride this bike rev-high and string it out if you like that sort of feeling and it continues to respond to throttle input instantaneously as it consistently builds strength. It doesn’t sign off at all. You can also shift up and let it eat in the middle while you lug and chug to jump faces. The beauty in this abundance is that it equals versatility, and this KX450F motor clearly proves that revvers and luggers can share the same ride. Compared to a 2009, the power simply feels boosted, especially in the mid-to-top surge and the smoothness of the strong bottom. This is a powerplant that will appeal to everyone from big, heavy vet riders to those little punks who whip it upside down over the big, heavy vet riders. Even racers looking for more or less can easily find it with the EFI tuning tool from Kawasaki.Unfortunately, the pumped-up power of our KX-F and the confines of an earthly motocross track equated to a seriously smoked clutch on the first day. The clutch plates were updated for 2010 with 75 percent more friction material to give more controllability and a more direct feel to the clutch-which it does. In fact, the clutch pull is simply delicious on this KX. It’s direct and smooth (thanks mostly to the revised pressure plate and other internal tweaks). The bad news is that while using the clutch to control the acceleration and power of the 450, the new plates got worked over in a bad way. Does more friction material equal more heat for clutch users and abusers? Our second day out with a new clutch pack wasn’t as bad, and Racetown 395 had more sweeping corners requiring less clutch use. Then, at Piru, we just left the bike in third all day and ignored the clutch while keeping revs down. But the first day showed us something to look out for, for sure. We’ll be monitoring the clutch life closely from now through the 450 shootout to see if this issue continues.We’re also keeping an eye on the suspension clicker settings and rider sag measurements on this bike. The reason here is simple: We’re having a tough time dialing in the fork settings to get a plush, controlled ride that is balanced front-to-rear.