2012 Kawasaki KX450F and KX250F Preview

Smoother, slimmer, faster and stronger


Kawasaki has updated its KX450F and KX250F motocross bikes for 2012. Dan Paris gives us the details on Team Green's latest MX machines.

Everyone knows the KX450F rips. Rips tracks to shreds, rips your arms off … In a horsepower race, team Green sits on top.

For 2012, Kawasaki has taken steps to civilize the monster for 2012, starting with a two-mode ignition dubbed ‘Launch Control, which is tuned to improve off-the-line traction without sacrificing mid range or top end power. The push-button system is activated by a switch on the left handlebar that alters ignition timing in first and second gear. When the rider shifts into third gear, the EFI returns to the standard ignition map. Sounds like exactly what we’ve been begging for!

The big Kawasaki has also taken flak for being, well, big. A new frame and slimmer rider compartment, with a width reduction of 4mm across the main frame spars, give the 2012 KX450F its most slender mid-section ever. Chassis rigidity has been refined by altering the shape of the ribbing inside the new frame, creating more flex in the upper portion and stiffening the lower sections around the swingarm pivot. The seams between the radiator shrouds, seat and side covers are very flush fitting to help prevent snags.

2012 Kawasaki KX450F
2012 Kawasaki KX450F

The KX450F now comes with four different handlebar positions and two footpeg positions to better-fit different sized riders. Mass centralization and a lowered center of gravity were Kawasaki’s goals for 2012, so a new fuel tank, upgraded bodywork and a shorter muffler were designed to shuffle weight toward the center of the motorcycle. The new fuel tank also has a shorter overall height and a narrower top section, with a smoother tank to seat transition to improve rider freedom of movement. The tie rod arm of the Uni-Trak® rear suspension linkage is now slightly less rigid to improve rear-wheel traction. Kawasaki also offers an optional shorter rear suspension tie rod to reduce seat height.

The DFI system comes with three pre-programmed ignition maps that are changed without the use of a laptop computer. Maps can easily be changed to suit standard, hard terrain or soft terrain by swapping the DFI wire coupler cap clipped to the side of the steering head. The ECU is also programmable by using the accessory KX FI Calibration Kit that works with any computer running Windows 7.

The 2012 KX450F has improved mid- to high-end power and a wider powerband, thanks to a new bridge-box bottom piston that has been revised to enhance mid to high-rpm power. A thinner top piston ring with an upgraded surface treatment is used to reduce friction and improve throttle response. A new intake cam boosts power as well. The new header pipe is shorter and features a tapered mid-section. It bolts to a new silencer that is 60mm shorter than last year but has the same overall volume and meets 94 dbA noise regulations.

2012 Kawasaki KX450F

The five-speed manual transmission has an extra dog on the gears and a shorter shift fork to improve shift feel. First gear is thicker to improve durability. A new shift lever moves the pedal 3mm farther from the footpeg, and heavier clutch springs keep clutch slippage in check.

2012 Kawasaki KX450F

The Kayaba shock receives the Kashima Coat surface treatment to its internals. Kayaba’s Air-Oil-Separate (AOS) fork keeps oil and air in separate chambers for stable damping performance, and 2012 Kawasaki KX450Fit’s mated to a revised lower triple clamp. The super-hard Diamond-Like Carbon (DLC) coating on the outer surface of the inner fork tubes and high-tech Kashima Coat treatment on the inner surface of the outer fork tubes help deliver supple action.

A blue alumite finish on the oil cap and generator cover caps highlight the upgraded appearance of the KX450F motor and match the blue finish on the suspension adjusters and new graphics. The embossed logo on the clutch cover features a raised Kawasaki insignia that is revealed as the black paint is worn away by the rider’s boot.

The changes announced for the 2012 KX450F address our few concerns about the 2011 model, and we can’t wait to ride it at the famous Red Bud AMA Motocross track next month. The 450F will be available in Kawasaki Lime Green, with black alumite-coated rims, blue anodized highlights and aggressive graphics at a price yet to be shared.

2012 Kawasaki KX450F

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