2010 Kawasaki KX Motocross Lineup

The KX450F and KX250F receive several changes for 2010, most notably what Kawasaki calls the first mass-produced bridged-box bottom piston. Used by Kawasakis factory racers, the bridged-box bottom piston design is said to be nine grams lighter and promises more power in the high and over rev rpm ranges. A wedge-shaped crank web, also inherited from the factory racing machines, acts as a counterbalance to sooth engine vibrations. Kawasaki says it offsets 60% of the crankshafts reciprocating weight.

The KX450F also receives revised cam timing and ECU settings which Kawasaki says will improve mid to high rev performance while a reinforced cylinder sleeve and right side crankcase offers more durability. The 2010 model receives a new stainless steel exhaust pipe that is 40mm shorter than the 2009 titanium pipe.

Kawasaki also updated the 450s chassis with a new lower-rigidity steering stem shaft and revised suspension tuning that promises added comfort and cushioning when landing jumps. The D-shaped aluminum swingarm has also been revised with narrower ribs and thinner walls. The Uni-Trak rear suspension linkage has also been revised to provide a long rear suspension stroke and to make precise tuning easier. Up front, Kawasaki revised the Kayaba Air-Oil-Separate fork to work with the new stem shaft, promising improved action and comfort in the first phase of the suspension stroke.

The 2010 Kawasaki KX450F is ticketed at $8,049.

The KX250F also received several updates, but it didnt get the one many people were expecting: fuel injection. The KX450F received fuel injection in 2009 but its smaller sibling will have to wait until at least next year to switch from carburetors.

Unlike the KX450F, the quarter-liter model receives a longer head pipe with a shorter mid-section. The suspension and chassis changes are similar to the KX450F, except with Showa parts.

The 2010 Kawasaki KX250F has a retail price of $6,999.

Among Kawasakis small displacment models, the KX85 receive an update to its graphics for 2010. The 2010 KX85 retails for $3,849. Kawasaki will continue to offer the 2009 KX100 and KX65 models.