Kawasaki rolled out the red carpet for its 2011 KX450F and gave the moto media its first chance to spin a few laps on the bike at Racetown 395 in the high desert of southern California, and we came away impressed with the bike, which was hardly a surprise. After all, the 2010 KX450F was already an outstanding machine, which received minor refinements for 2011.
Kawasaki focused on making the '11 easier to ride by making subtle changes to the suspension and motor. Basically, Kawasaki came up with new fork and shock damping settings, and tweaked the FI's ECU settings. They also made some changes to the bike's shifting mechanisms to improve shifting. It also got a new muffler.What stood out most when riding the new KX450F for the first time was its motor. First of all, it's extremely easy to start. All day long and in the heat, the bike started right up after no more than one or two light jabs on the kickstarter, and you didn't have to apply any throttle at all - just a good efficient kick does the trick.When it does fire, you'll immediately notice how much quieter the new muffler is. Kawasaki says the KX meets the new 94dB noise regulation, and we believe them. Even though the KX is quieter, it still sounds like a motocrosser, not like a plugged-up trail bike.On the track, we found the new KX to be quite easy to ride, which a lot had to do with the smoother-performing motor. It has tons of power off the bottom but doesn't really have an explosive hit anywhere in the powerband. It doesn't want to just rip out of your hands every time you twist the throttle. Instead, the KX is very manageable and smooth, especially in the first half of the powerband, where you can ride this bike all the way around the track. You really don't have to shift it all that much to make it go fast, which we quickly found out, even though Racetown 395 is fairly fast and spread out.
But, you can rev it out if that's your style. There's plenty of power on top, too. It can be ridden at both ends of the spectrum, but we preferred short-shifting the bike and letting all that bottom-end power do the work.It also shifted with precision; gear changes were smooth and light on the toes. We experienced zero missed shifts on the day.Suspension was extremely good, too, at least on this track which had a lot of chop, some rolling whoops, and a few large tabletops. The bike felt very stable at speed and had no problems soaking up the smaller bumps and square edges.The bike cornered well, too, but the front end had the slight tendency to push, though we noticed the forks appeared to be positioned rather high in the triple clamps. But there is plenty of range for adjustment. In other words, this pushing tendency should be easily remedied with some closer attention to fork positioning and rear sag. But for now, we had no real complaints with the bike's chassis or suspension.Overall, though, we came away quite please with the new, easier to ride KX450F. We do have a lot of plans for this bike, but, from what we can tell so far, it's safe to say that if you liked last year's bike, you're going to like the '11 even more.
Here's what Kawasaki has to say about its 2011 KX450F, followed by specifications:Last year, the KX450F featured a number of engine refinements, including the first ever production use of a bridged-box-bottom piston (more high-end power and better over-rev characteristics), revised cam timing for better mid- and top-end performance and a reinforced cylinder sleeve and crankcase for improved durability.This year there's even more. Piston shape, for instance, has been modified to meld with the upgraded, higher-volume muffler, which is quieter than last year's unit.The ECU has been tweaked to provide a hotter and longer-duration spark for improved low-rpm response. The shift mechanism incorporates a larger internal roller and stronger shift-spring tension for more positive shifting. Finally, the fuel-injection system's Calibration Kit software has been updated, while the controller harness and connector have been modified for easier use.Changes in the chassis department are equally impressive, and show the results of our race team's effect on development. First up are revised damping settings for the massive fork tubes for even better performance. For that factory-bike touch there are also blue-anodized compression damping adjuster caps in place of last year's silver ones. Damping settings on the rear shock have also been revised, and it, too, gets a blue-anodized compression adjuster. The seat features a new side-surface texturing for increased rider grip while aboard, and the drive chain guide has been thoroughly beefed up for increased durability; testing shows it to be nearly three times more durable than the unit fitted to the 2010 machine.The race-ready engine is compact and light, with a short 100mm cylinder head and a 12.5:1 compression ratio. A wedge-shaped crank web offsets 60% of the crankshaft's reciprocating weight, producing an effective "counterweight" effect. This is on par with Kawasaki's factory racers and helps reduce engine vibration, smoothes power delivery and enhances low-rpm throttle response. A stainless steel exhaust pipe connects to the revised silencer, which uses long-fiber packing material to maximize service intervals. A rubber damping collar in the rear silencer mount provides a boost to long-term durability. The KX450F's Digital Fuel Injection (DFI®) automatically adjusts to suit track and climate conditions, and offers stable fuel metering even when landing from jumps in tough motocross conditions. The DFI system includes a compact and lightweight ECU, a 43mm throttle body, a lightweight aluminum fuel pump and an ultra-fine atomizing injector. Set at a 45° angle for ideal mid-range power, the 12-hole injector sprays precise, 60-micron fuel particles for smooth power delivery and accurate engine response throughout the rpm range.Designed specifically for motocross, the KX450F's lightweight DFI system doesn't require a battery; the engine can be started within three rotations of the crankshaft using only the electricity generated through the initial stroke of the kickstarter.An optional ECU Setting Tool allows racers to select from several different ECU data maps, or fine-tune a custom map that alters fuel injection and ignition timing to suit different tracks and conditions. The tool can also be used as a data logger, recording up to six hours of data, including engine rpm, degree of throttle opening, engine boost, coolant and air temperatures, ignition timing, fuel adjustments, gear position and system voltage.The engine's phenomenal power is delivered through a clutch that features an ultra-light operating plate with superb oil drainage and beefy friction plates. The entire assembly is designed to provide exceptional clutch feel and durability. The drive chain features thin inner links and a slight weight savings relative to typical designs to help boost acceleration. The revised suspension damping settings provide lighter handling, improved suspension action, increased comfort and greater cushioning when landing from jumps.The 2011 KX450F's D-shaped aluminum swingarm features a cross section with narrow ribs and thin walls. It pivots high in the aluminum frame to maximize rear wheel traction. Mounting the arm of the Uni-Trak rear suspension linkage below the swingarm provides a long rear suspension stroke and facilitates precise shock tuning.Complementing the responsive chassis is a Kayaba Air-Oil-Separate (AOS) fork that offers precise cornering and sharp handling. The fork features a Diamond-Like Carbon (DLC) coating on the outer surface of the inner fork tubes to minimize stiction when the fork is exposed to lateral forces that would otherwise restrict slide action. The result is smooth and precise response, especially during cornering. Overall suspension action is extremely smooth due to a friction-reducing Kashima Coat treatment on the inside surfaces of the outer fork tubes and the rear shock reservoir. Wrap-around fork guards provide excellent protection for the sliders.The 2011 KX450F's Kayaba rear shock's revised damping settings contribute to improved wheel control and impact performance when landing from jumps. It features a large 50mm piston and a Kashima Coat treatment on the shock internals to help maintain a plush feel throughout the toughest motos. Easily accessible dual compression adjusters allow high- and low-speed damping to be tuned separately, giving mechanics and riders the ability to easily fine-tune the suspension for difficult track conditions.A slim seat design with firm urethane foam and a non-slip top and side surface provides even more seated and standing grip while retaining excellent rider mobility.The frame echoes the slim profile at the top, but widens at the lower end by the ankles to provide the rider with better feel and control. Completing the rider interface are wide 50mm footpegs that offer tenacious grip and a comfortable platform.
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