Factory-style components and tuning for every racer

Kawasaki's KX'250F motocrosser had a victorious year, winning on the track and topping its class in numerous enthusiast magazine shootouts. The successful mix of the highly rigid aluminum frame and top-shelf suspension components deliver superb high-speed stability, while its chassis geometry and high-revving engine offer excellent rear wheel traction and holeshot-winning performance. Christophe Pourcel used his new Monster Energy/ Pro Circuit / Kawasaki KX250F to win the AMA East Supercross Lites Championship and then continued his winning ways into the outdoor season. But in the volatile world of racing, it's a constant challenge to stay on top.

To ensure it continues its podium-topping tradition, Kawasaki fine-tuned the light handling KX250F for 2010. The engineers capitalized on its solid foundation, with refinements focused on increasing performance and longevity. The result of their labors will help the KX250F add to its ever-growing trophy collection.

Borrowing from the racing world, the KX250F gets a new piston with a bridged-box bottom making its first appearance in a mass-production machine. The new piston is lighter and stronger. It also has a revised profile with a shorter skirt and shorter piston pin, which reduces reciprocating weight. It also features a revised crown that improves combustion. The cylinder height was raised accordingly to maintain the 13.2:1 compression ratio. Low-rpm performance was bumped up via a new longer head pipe and shorter mid-section on the new, more durable stainless steel exhaust pipe.

The 249cc, liquid-cooled, four-stroke engine received a number of other refinements for 2010, such as electrofusion treatment on the cylinder bore, revised oil pump rotors and a wider big-end bearing to increase engine life.

Its crank web design produces a crankshaft balance factor of close to 60 percent, on par with Kawasaki's factory racers. The result is reduced engine vibration, smoother power delivery and increased performance in the mid-high rpm range. Tuned to deliver the widest possible torque band, the KX250F engine offers traction in a controllable, class-leading manner from the first crack of the throttle to wide-open at the rev limiter.

Like its bigger sibling, the KX250F received larger, stronger radiators with increased fin and tube pitch that accumulate less mud and provide more consistent cooling. With the extra strength in the new radiators, the reinforcing brackets could be dropped, helping reduce the weight of the entire radiator assembly.