First Test: 2011 Kawasaki KX450F

The poor guys in Kawasaki's testing department. Since the introduction of the FI KX450F in 2009 the machine has won in WORCS, GNCC, OMA, National H&H, Supercross and National Motocross, but the bike has been overshadowed in magazine shootouts. Complaints of too fast, too stiff and other minor drawbacks torpedoed the (sometimes slightly too mean) mean green machines. Apparently the third time really is the charm, because Kawi hit the KX450F target dead center for 2011. On paper the changes look small, but on the track this is a whole new feeling. Clearly, the many varied championships and race wins prove the potential of the basic package, but in stock form the 2010 was stiff and harshly suspended for most riders. For a smaller number the power was overly enthusiastic and not at all suited to tight and technical tracks.

Kawasaki kept it simple for 2011, starting with a new piston, a longer, larger-volume muffler, ECU changes and a shift mechanism upgraded with a larger internal roller and more shift spring tension. While still not exceptionally quiet, the '11 has lost the raspy, blown-out sound. The KYB suspension already used prime components like the AOS fork with a slick DL coating on the lower legs and a shock with a 50mm piston, so the suspension changes were limited to revised damping settings front and rear and some anodized goodies to add a little zip to the look. Chassis upgrades were limited to stamped-steel head-stay plates that replaced machined-aluminum parts. The steel plates are said to add a more compliant chassis feel. As far as rider accommodations go, the seat foam is a bit firmer for longevity, and the seat cover has improved traction on the sides.

It doesn't take an extended test session to feel the suspension improvement. Your first laps will reveal the plush feel of the suspension. Bottoming resistance is still excellent, but the formerly hacky fork has become a super soaker on braking chop. The action is so supple and smooth on initial movement that front end traction is up and the bike feels better than ever in flat turns or when aiming for insubstantial ruts or minuscule berms.

The shock demonstrates a much nicer action as well. It also has a plush feel with very little of the track surface reaching the rider. The rear of the bike is controlled under braking as well, but corner exits and acceleration are the most impressive facets of the shock's performance. The rear settles under power, gets amazing traction and drives straight and true with no drama. All of the suspension adjustments we made were to settle the chassis. The initial testing was on the fast and rolling bumps of Racetown 395, and at times the bike felt a little loose and it was hard to trust the side traction. A couple of clicks stiffer at both ends and slightly slower rebound for the fork settled things down. For heavier pilots a quarter-turn of high-speed compression held the rear up without letting the bike feel harsh.

Our feeling is that the initial violence of the 2010's power compounded the harsh suspension feeling. For any little kick the engine broke traction and made things worse. For 2011, the power from way down in the rpm range is smooth and tractable with an easy roll-on. There is still plenty of energy there for most riders, and if you need more, turn the handle. The transition to mid is smoother but still builds strongly, and from there on up the engine revs smoothly and cleanly, like it has to work less to spin high rpm. Once revving, the acceleration is massive. The rear suspension doesn't allow the rear to lose traction as easily, but the character of the power works with the suspension to keep things in hand. As a result you can think more about racing and less about controlling the bike.

Better suspension equals better... 

   

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Getting over big jumps is as easy as ever with the smooth rush of middle and top rpm power, but now the bike is much more capable in rhythm sections that require precise timing. Riders looking for 2010-style boost should find it easily enough with FI tuning, but we'll stick with the '11.

What the Kawasaki doesn't have is the new-age chassis feel of the Yamaha and to a lesser extent the Honda CRF450R, that lighter feeling and shorter wheelbase sensation. That isn't a bad thing, but an observation. The KX feels a bit long, stable and physically a little larger than some of the lightest and most flickable models. That does not make it any less effective on the track, but like any bike you play to its strengths. That should be easy with the suspension bumping up the front end traction. Overall the KX450F just works extremely well as a package, so in spite of minimal changes it has a better shot at a shootout win than ever.

Though the looks are similar... 

   

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Specifications:

2011 Kawasaki KX450F
MSRP: $8,149
Claimed weight (curb): 249.9 lb
Actual weight (tank full): 250 lb
Seat height: 37.4 in.
Seat-to-footpeg distance: 20.6 in.
Footpeg height: 16.8 in.
Ground clearance: 12.0 in.
Ground clearance: 12.0 in.

What's hot!

Much smoother and easier-to-use power but still plenty of boost.
Suspension settings and spring rate choices that offer super-plush action.
Suspension changes make the bike feel lighter and turn in easier.
This bike hooks up very well!
Roomy riding position that suits tall riders without alienating compact ones.
Sound levels are down, and the exhaust note is less raucous.

What's not!

With all the black on the bike it looks dirty quickly and shows wear. It still isn't the quietest machine on the track.

SETTINGS
SUSPENSION	STOCK	DR
FORK
Comp.	10	8
Rebound	10	8
SHOCK
Low-spd. comp.	10	8
High-spd. comp.	1.2	.8-1.2
Rebound	18	17-18
Sag (mm)	95-105	102-110

Read more: http://www.dirtrider.com/reviews/motocross/141_1012_2011_kawasaki_kx450f_first_test/index.html#ixzz1SM1Y8ffU