Life for manufacturers used to be easier when it came to selling motocross four-strokes. At one time both Yamaha and Honda dominated the market. But now every color has a 450F and they’re all great. It was rumored that Kawasaki postponed the release of its 450 for one year after it could have produced it. It wanted the bike to be right, and the extra year paid off. Despite being the last Japanese brand to enter the 450 class, Kawasaki has made, and continues to make, a big impression. The KX450F has had few problems and a great deal of success. Many of its triumphs have been earned in motocross/supercross (James Stewart, Michael Byrne and Tim Ferry) and arenacross (Darcy Lange and Josh Demuth), but the model has also earned a Hare & Hound title (Destry Abbott) and a WORCS championship (Ricky Dietrich). Clearly the basic package is complete. The changes for 2008 are what we’d call thorough fine-tuning, but the difference in performance is significant and surely sufficient to keep the KX-F battling with the best in the class.Even though aluminum frames have had a very positive effect on the sport, the technology is still evolving with the primary focus on torsional rigidity. The challenge is to engineer enough twist into the frame to aid turning and traction. Kawi moved the engine mounts 10mm farther from the engine to allow more flex in the chassis. Even with the black “Diamond Like Coating” on the fork legs, the suspension wasn’t perfect in 2007, so the inside surfaces of the upper fork tubes and shock reservoir gained a low-friction Kashima coating for ’08. The overall suspension settings are slightly stiffer as well, and an effort was made to further balance suspension action front to rear.In 2007 the suspension performance was challenged by an engine with such massive pull that the rear end had to cope with that load and bumps. For ’08 the engine gets pork chop- shaped crank webs and a heavier flywheel to smooth the delivery and aid traction without reducing overall boost. A variety of small changes to the rod material, oil pump, shift drum and the ignition enhance reliability, add confidence in the shifting and allow easier starting when hot. And then, of course, there are those black rims to spark up the look.The attention to detail lavished on the engine is obvious as soon as the bike starts. The KX lights easily, has all but perfect jetting and crisp and immediate response. It’s also apparent that the bike is loud. Kawasaki was quick to point out that the thumper passes sound. We suspect that the ignition is engineered to make the bike meet AMA regs at the test rpm, but the bike is much too raucous in higher rpm ranges.If you tune out the sound, you can start to enjoy the KX just fine. The changes to the crank and flywheel have worked magic on the power delivery. The engine rolls on super smooth out of turns, grip and traction are abundant and reliable and the rider can choose the moment for the jump to light speed. Once the throttle is opened past the halfway mark, the track gets gobbled up at an amazing rate. The pull is never violent like the bike is trying to tear your arms off, but you end up really hauling on the straight parts of the track. Adding flywheel effect has merely calmed the power. Ample snap to clear jumps right out of turns is still on tap. We never considered lower gearing, but a few riders could conceive of wanting a tooth or two less on the rear sprocket.A few riders noticed a reluctance to transfer from second to third gear in a hurry, while others wondered why you would bother using second gear. Shifting earlier and being sure of the shift ended most complaints.
Whether the chassis or suspension changes are most responsible, the ’08 KX450F is the best turning edition to date, and it has always been happy in turns. A low-in-the-rear, high-in-the-front feeling some riders noted in ’06 and ’07 is gone, and the chassis feels level and balanced for corner entrances. Front wheel feedback is solid, and riders tend to trust this bike in any sort of turn situation. When a bike has quick turning, stability can suffer, but that isn’t the case here. Kawasaki managed to keep the bike happy at speed as well.Having slightly stiffer suspension and the extensive use of friction-dodging coatings paid off with excellent performance. The bike rides up in the stroke in the rough but settles for corners like it should. For jump faces the action is lively enough to let you load the suspension and get extra lift, but it remains calm enough for sharp and abrupt takeoffs.As far as the rider accommodations go, the KX feels a bit more compact than other brands, but not overly so. Nothing interferes with the normal ranges of movement we use while riding. In other words, Kawasaki took a bike we thought was really nice and made it even better. It has excellent handling, massive but controllable power and fine suspension. About the only consistent complaint concerned the exhaust note. At high rpm the bike is loud, and the muffler sounds blown out even when brand-new. It will take a shootout to really find out where the bike falls, but right now it looks very strong for 2008.What’s Hot
Suspension action is smooth and controlled.Engine is house-trained but still a meat-eater when revved.Starting is very easy hot or cold.What’s Not
Exhaust note is loud and sounds odd.Specifications
Claimed dry weight: 220 lb
Actual weight (ready to ride, no gas): 236 lb
Seat height: 37.8 in.
Seat-to-footpeg distance: 20.5 in.Opinions
Last year, I didn’t really get along with the big KX-F. With snappy power and iffy handling, I didn’t like to ride it much at all. This year, with small yet simple changes, I think the bike has improved in most areas and taken a big step backward in others. First, the good stuff: I love the new power delivery on the KX-F. The heavier flywheel delivers the ponies with less of a punch, and I think it’s just enough calmness to bring this bike back into contention as a shootout winner. Also, the handling is better. The increased flex in the frame is making this dude lace into turns better than ever. Straight-line stability is sweet, too. On a sour note, the KX450F sounds like a clapped-out piece of crap with a broken muffler. The stock sound is horrendous and bugs me to the point of not wanting to ride the bike. I’m not ignorant enough to think noise is power; no one else should be, either. By being creative with ignition maps and electronics, I’m sure Kawasaki has the bike sound testing just fine, but open the throttle when you’re actually riding the bike, and you’ll be greeted with the strangest muffler tone ever to come out of a stock bike.
-Jesse Ziegler/5’10”/175 lb/Squid of the MonthKawasaki made some very nice changes for 2008, and the KX450F is a definite weapon. The power is vastly improved in terms of ease of use, but not dumbed down as far as sheer output goes. The balance and feel of the bike is more level and neutral than ever, and that rear end’s tendency to kick up over sharp bumps is pretty much cured. I don’t like the volume or the tone of the exhaust note, and the bike is a little scrunchy with a too-soft seat. What that means is I could easily fix any problem I have with this bike. And the bike is definitely worth taking the time to make it work.
-Karel Kramer/6’1″/210 lb/Novice
I typically don’t spend much time practicing aboard 450cc machines, which might be why this bike scared me so much the first time the power hit. The motor launches out like a wound-up Jack-in-the-Box, yet it does so in a much more ridable fashion than the ’07 model. The curve of the updated motor seems to start out with a strong, smooth initial hit before settling into a clean acceleration path that leads to yet another high-rpm blast of power. The 2008 chassis improvements also lend to the bike’s newfound stability, as the frame feels more responsive and not quite as jarring through chop and square-edged holes. For my weight and preference, I found that the best suspension setting was two clicks in on the rebound at both ends, as well as two clicks softer on the low-speed of the shock (I chased the fork compression back to stock). With this setup, the Kawasaki felt very hooked up in the rear wheel-especially noticeable in off-camber, odd-angled corners-and the bike skipped across braking bumps rather than into them. In my opinion, there are a few hitches to the KX450F that need to be worked out. The machine feels long, tall and heavy on the track. As a result, I don’t feel totally confident in the bike’s handling, but then again I’m a bit smaller than the target 450cc rider. Also, I felt the Kawasaki pop out of gear between second and third a few times, and the exhaust tone is downright rotten. But as far as improvements go, Kawasaki did a great job fixing last year’s issues, and it most certainly produced one heck of a fast motorcycle.
-Chris Denison/5’10″/155 lb/IntermediateKawasaki improved its new big bike for the ’08 year. Last year the suspension had an unbalanced feel to me, but not this year. I noticed that the suspension feels like it’s working in harmony to soak up the big slap-down landings. More importantly, I could accelerate out of the corners that had nasty chop out of them. On deceleration the shock didn’t kick me or do anything funny. It was as predictable as I like it! The motor was improved down low. It had great throttle response but also kept that smooth roll-on feel that I like out of 450s. The third thing I noticed was that it did miss shifts. Between second and third gear was a difficult time for the KX450. Overall, I think Kawasaki did a great job making improvements on the newer KX450F.
-Kris Keefer/5’11”/170 lb/Pro