2004 Yamaha YZ450F, Keeping our ears to the dirt has been critically important over the years, and weve been picking up some seriously strong vibrations ever since we built the worlds first modern four-stroke motocrosser. Making improvements is how we continue to evolve a tighter, quicker, easier-to-deploy package. The YZ450Fs high-revving counterbalanced 449cc liquid-cooled five-titanium valved 39mm Keihin-carbureted single is pure moto winning magic. Upgrades for 2004 consist of a rigid 48mm fork with new settings for a smooth, compliant and progressive feel. New, titanium footpegs and gripper-style seat cover material improve the crucial interface between man and machine -- and man, what a machine: 222 pounds of high-tensile steel-framed, loam-launching, terrain-following, thrill-seeking motocross machine. Yamaha-exclusive five titanium valve head (three intake, two exhaust) reduces reciprocating mass and helps make 11,000 rpm a regularly recurring event. Bringing a 95mm piston to life against 12.5:1 compression can be hard work; YZ450Fs genius auto-decompression system and hot start lever make it quite easy. And four speeds are plenty, given the YZ450Fs seismic spread of power -- and a heavy-duty clutch that gets the power to the ground consistently. Its fast, its furious, and its Motocross Action magazines 2003 Bike of the Year.