The 2011 Kawasaki KX is an offroad motorcycle designed for motocross racing. It is available as the 2011 Kawasaki KX 250F with a 249-cc engine and as the 2011 Kawasaki KX 450F with a 449-cc engine. Both are four-strokes. There also three different two-stroke variants: the KX 85 with an 84-cc engine, the KX 100 with a 99-cc engine, and the KX 65 youth model with a 64.7-cc engine. All are liquid-cooled and kick-start only. Four-stroke bikes have five-speed transmissions. The two-strokes have six speeds.
The 2011 Kawasaki KX 250F is vastly reworked from the previous year. The biggest news is changing from a carburetor to a very advanced Digital Fuel Injection (DFI) system that automatically adjusts to changing track and climate conditions. This is virtually the same system already available fitted to the KX 450F. The system is designed to be easily tunable in the shop or at the track. Several different pre-defined data maps are available to fine-tune fuel injection and ignition timing. Custom data maps are also possible. These functions are accessed via an optional ECU Setting Tool that downloads data into a laptop computer. It can also be used as a data-logging tool to record data collected while on the track. Another big change is the Separate Function Fork (SFF). In a typical motorcycle suspension both front fork legs handle both springing and damping functions. In the SFF system these tasks are isolated to individual fork legs. The right leg only needs to provide springing action. The left fork leg damps the motion. Both rebound and compression are adjustable.
All of this advanced technology has helped make Kawasaki dirt bikes some of the best around. Kawasaki factory-backed race teams have won multiple motocross titles. Top racers start riding at an early age. To help these aspiring racers develop their skills Kawasaki offers smaller, lighter versions of its KX race bikes. Two-stroke engines power the KX 85 and KX 100 motorcycles. Two-strokes have a higher power-to-weight ratio than four-stroke engines so these motorcycles still deliver great performance and are very fun to ride. Both are scaled down somewhat from the bigger four-strokes and are much more manageable for riders still climbing the learning curve. For the very youngest riders there is the KX 65. It has much of the same race-proven technology as larger Kawasaki dirt bikes in a machine that weighs just 133 pounds.