Last year’s version blew the doors off with all-new fuel injection, but for 2010 the KX450F isn’t changed as radically. This burly beast is only refined for the new year with adjustments you can’t see from the outside. Inside the motor is a new bridged-box piston. It shaves seven grams and has a 6mm-shorter skirt. Kawi claims it increases performance at the top of the rev range. The intake cam timing is advanced two degrees and ECU settings are tweaked. Kawi says the piston design has been proven through use in the race team bikes along with a wedge-shaped crank which is already in use. By offsetting 60% of the crankshaft’s reciprocating weight, it acts as a counterbalance to smooth the engine delivery and vibrations.