KX250F

Tuned to best suit race-experienced riders, the 249 cm3 liquid-cooled, 4-stroke Single’s wide powerband focuses on high-rpm performance and extends way into the over-rev. Highly acclaimed for its high output and power delivery (thanks to race-inspired tuning and parts like the high-performance piston with bridged-box bottom), the 2012 KX250F takes MX engine performance to the next level with the world’s first dual injection for motocrossers. The power increase – recognisable by riders of any level – is complemented by the smooth FI response of the 2011 model. Further engine changes offer smoother shifting and increased reliability.

The KX250F fuel injection system features dual injectors: an injector downstream of the throttle valve (where injectors are located on standard FI systems), and an upstream second located close to the airbox.
Unlike the dual injection found on supersport models (where the upper injector operates only part-time, providing additional fuel when necessary), the two injectors in the KX250F fuel injection system have different roles. The downstream injector is used to ensure smooth, instant response while the upstream injector is charged with providing power. As rpm and throttle position increase, operation switches from the downstream injector to the upstream injector. (Depending on whether in a low (1st, 2nd) or high (3rd, 4th, 5th) gear, the switch is progressive or almost instantaneous.)