Executive summary about the 2010 KX250F by Jeff Buchanan
The new piston has a shorter skirt and narrower piston pin to reduce reciprocating mass, resulting in a quicker revving motor. The piston’s crown has been reshaped, adding 0.6mm in height to improve combustion with the cylinder height increased slightly to maintain a 13.2:1 compression ratio.
A new exhaust pipe – made from stainless steel for increased durability – is comprised of a longer head pipe married to a shorter mid-section to boost low-rpm performance. The technicians at Kawasaki boast that they’ve gotten the KX’s crankshaft balance closer to that of the factory racers, resulting in less vibration, which translates into smoother throttle response.
The 250 gets larger, wider radiators with a fin pitch designed to accumulate less mud. The increased rigidity of the new radiators allows the reinforcing brackets and support stays to be removed, resulting in reduced overall radiator weight.
By reducing the size of the steering stem – from 24mm to 23mm – rigidity is reduced, theoretically giving the bike a slightly lighter feel in handling. As for the basic numbers, seat height is 37.6 inches. Showa twin-chamber forks have titanium-coated lower tubes that reduce friction for smoother response. The 16-way compression and rebound damping adjustments augment 12.4 inches of fork travel. The damping settings are new, with less forward lean that lends more balance in the bike’s front to rear attitude. The rear shock possesses 13-way low-speed and stepless high-speed compression damping with 17-position rebound damping and fully adjustable spring preload, providing 12.2 inches of rear wheel travel.
Adding to the durability factor, the KX250F is fitted with a resin skid plate, rear brake caliper guard and longer-wearing chain guide. Black triple clamps paired with black alumite-coated wheels and Renthal aluminum bars help the production KX to closely mirror the factory race machines.
We enlisted the services of Intermediate-level racer Parker Jones to flog the Kawasaki around the private Castillo Ranch Motocross track in Central California. At 16 years-old, Jones stands 5-foot-11-inches tall and weighs 165 pounds.
Parker was pleasantly surprised by the KX’s power and tracktability that required him to shift his weight forward on the uphill section to keep the front end on the ground.
As for cornering, Parker said the bike worked equally well whether railing a berm or taking the point-and-shoot approach to a corner. The bike responded well to rider input, going where the rider wants it to without a fight.
Although the rear brake worked decently, Jones commented on squeaking noises on corner entry. The 2010 Kawasaki KX250F is a more refined, focused, and durable machine from its worthy predecessor.