have to agree with this, my 400ex with a 440 bore kit, stage 2 cam, exhaust, air filter and jet kit has beat a raptor 660 with a pipe and air filter and a yfz450 with a pipe, air filter and jet kit. and I have at least 150lbs on both of those guys. and even with those mods my quad is still more reliable than both those yammis
Well then that 450 was not running right. The 400ex, warrier are old design engines and are oil cooled not water so they run hot and rob power hense why you dont see them anymore on the track.