Kawasaki KX450F 

Kawasaki was the heavy favorite coming into this battle of bruisers. As last year's clear-cut winner, the bull's-eye was clearly painted in green and black. Certainly the accolades earned in the past year through the media and at the professional racing level have proven the 2006 version to be a rock-solid starting point in Kawi's new 450 Thumper endeavors, and James Stewart has already taken the 2007 machine to all-new heights.

The big news that everyone's been talking about is the new 5-speed transmission and a motor that won't take any crap. Obviously, the two are tightly intertwined, but starting with the engine, we found out right away at Area P that the KX-F makes a boatload of power. Last year's mark of 49 peak ponies was third best but still super close to the highest mark set by the Honda. It churned out an identical HP figure this year (different dynos, mind you), but once it hit the track we could tell the Kawi engineers had this bike on a workout regiment during the off-season. It isn't a roids-injected difference, but Creatine shakes and a high-protein diet were certainly part of the equation.

Power comes on strong shortly off idle after a small lull was noted by several of our riders. Once past it thrums into the high rpm without any signs of abnormally aggressive behavior. Note the term "abnormal." Deciding where the optimal rpm range lies is hard to pin down since the entire powerband is aggressive and very linear.

"The power was very linear and this would have won the motor category (for me), but when we went to Glen Helen I found that the bike was a little hungry for power down low," says Zalamea. "Sometimes I would come into one of the sandy berms and try to mash the throttle to get me out and it would have a little hiccup."

The KX hits its peak at 8300 rpm, but the trip up isn't something you'll miss. What makes the bike a true rocketship is the amount of torque it produces. Again topping the dyno charts, a full 33 lb-ft barks out of corners and hustles you around the track in short order. Only one of our pro riders thought the Kawi could use a little extra through the midrange and top.

Sun called the Kawi a "berm-shot weapon" thanks to its stout, tractable motor and stable handling.

"It has a sweet, nice, broad powerband that's very workable," he elaborates. "The Suzuki has more bottom, the Yamaha has more top, the Honda has more midrange, but this (KX) probably is the most linear. It doesn't win in any one of those categories but maybe it will give you the quickest lap time at the end of a moto. People always forget that a usable powerband all the way through is what gets you through a moto with the least amount of energy expense and good lap times."

Interestingly enough, the KX-F didn't tally the highest marks in the motor category from our testers scorecards. In fact, it finished last, but its engine was continually one of the first comments made about the bike, which should give you an idea of how good the rest of these machines are.

As far as the transmission and gearing goes, our Kwacker got knocked a bit for its comparatively stiff and notchy action at the toe. Unfortunately, as the interface between man and machine the somewhat clunky application overshadows some of the transmission's positives. The gear ratios proved to be a highlight as they allowed the motor to keep dishing out the power in an extremely usable way. There was some concern that the new bike wouldn't tolerate lazy shifting as well as the old 4-speed, but to our pleasant surprise the Kawasaki will still carry that extra gear or stretch to the next corner without necessitating additional shifts.

The largest complaint about the Kawi, literally, is that it feels heavier and bigger than the rest of the bikes. MotoUSA's electronic scales proved that our testers weren't a bunch of crack-monkeys and revealed that the engineers' muscle-building program brought some additional weight. The bike is 4 pounds heavier than last year's model and 1-7 pounds more than our other test bikes. Several testers believe its weight is carried high on the machine and gave it a top-heavy feel. The complaints tended to come from our smaller, lighter riders who struggled not only with the weight but straddling the Greenie as well. With a seat height of 38 inches only the Yamaha is taller (38.9").

"It feels big - kind of heavy and a little wider," explains the 150-pound Horban. However, our heavier riders had a less negative opinion on the issue. Though noticeable, that extra poundage and girth at the knees was hardly detrimental to the bike's smooth, stable nature. The chassis and suspension components did an admirable job of handling the weight deftly and with grace. But, while the laziest rake and greatest amount of trail in our test plays a large part in keeping the Green bike on course, it's also a contributor to our riders' interpretation of weight.

"It was very plush and predictable, so I could do whatever I wanted with the bike," says an enthused Sun. "It didn't do anything strange of funny, and you could change directions any time you wanted. Besides, I like to have something to hold onto with my knees."

New Diamond-like Carbon coating (DLC) protects the fork sliders and eliminates stiction, which not one rider complained of. It also scores huge points in the style category. Though forcing the burly KX-F into an inside rut wasn't as easy as, say, the 229-lb Honda, it made up for it with high-speed stability and a confidence-inspiring attitude. It takes a much larger obstacle to shake the Kawi than most other bikes, and it's capable of handling almost anything across the motocross spectrum. Unfortunately, a strong, smooth and stable package isn't enough to keep it on the same course charted in 2006, and it's surprising how it fell in our '07 rankings.

Overall Rank: 3rd

Categories Won: Braking

KX450F Notepad:
E-Z adjust throttle cables
Choke knob impossible to reach.
DLC fork is wicked
MSRP $6899