Liquid-cooled, four-stroke single with DOHC and four-valve cylinder head
77.0 x 53.6mm
DFI® with 43mm Keihin throttle body and dual injectors
Five-speed with wet multi-disc manual clutch
28.7 degrees / 5"
48mm inverted Showa SFF telescopic fork with 40-way spring preload adjustability and 22-position compression and 20-position rebound damping adjustability/ 12.4"
Uni-Trak® linkage system and Showa shock with 19-position low-speed and 4-turns high-speed compression damping, 22-position rebound damping, fully adjustable spring preload / 12.2"
Single semi-floating 270mm petal disc with dual-piston caliper
Single 240mm petal disc with single-piston caliper
**Curb weight includes all necessary materials and fluids to operate correctly, full tank of fuel (more than 90 percent capacity) and tool kit (if supplied).
Kawasaki's KX™250F was the first mass-production motocross bike to feature Dual Injectors. One injector is located downstream of the throttle valve (where injectors are located on standard FI systems) and a second is located upstream of the throttle valve, close to the airbox. The two injectors split their roles: operating at different rpm ranges, they ensure both smooth, instant response at low rpm and high peak power as the revs climb.
For cases that call for low-rpm operation, like immediate acceleration off the start and precise control coming out of corners, primary operation falls to the downstream injector. Because it is positioned close to the combustion chamber, sprayed fuel can be supplied to the engine quickly, resulting in sharp response. Conversely, when high power is the priority, primary operation switches to the upstream injector, which focuses on high-rpm applications. Its location farther away from the combustion chamber means that the fuel has a longer travel time. This allows more time for the fuel particles and air to mix, as well as allowing the mixture to cool and condense. This means that when more power is needed, the cylinder can be filled with a greater quantity of a high-quality mixture.
In motocross racing, getting a good start is critical. A few tenths of a second can make the difference between getting the holeshot or getting buried in the pack. In slippery conditions, getting the maximum drive from a motocross bike requires precise control of both the clutch and throttle.
Launch Control Mode helps riders get out of the gate quickly by complementing high-level technique with engine management. Featured on a mass-production motocross bike for the first time on Kawasaki's KX™450F, the system activates a separate engine map designed to get a more efficient start off the line. The system is designed to the same specifications as that used by Kawasaki Factory racers competing in the AMA Supercross and Pro Motocross championships.
Launch Control Mode is activated simply by pressing a button on the handlebar. The Launch Control map slightly slows down the ignition timing to help tame the engine's strong torque and reduce wheel-spin off the start. Launch Control Mode is only active in the first two gears off the start, disengaging and returning to the standard engine map automatically once the rider shifts into third gear. The system gives riders a great advantage out of the gate and puts them in a better position to control the race.