I got a chance to trade my streetbikefor either a YZ450 or a CRf450, both bikes are 06. The CRF has a hig comp. piston, renthal twinwalls, new clutch, new plastic, newer chain and sprockets,nice levers, suspension set up for a heavier guy (190-195 A-rider): was a A-class race bike. good tires also. The YZ is all stock except for some graphics, aftermarket airscrew, re-done suspesion (again, heavier a-class rider), and good tires. -Both bikes have some wear on clovers and frame which is expected. The YZ has a little more on the covers. The guy with the CRf told me all the history, the guy with the YZ has doesnt know much because he was second owner, but previous owner told him it was a spare bike. My question is how would the YZ450f hold up? I Felt better on that bike, but I am afraid of 4-strokes blowin up! I want to know how the YZ450f's reliability is compared to others. could the bike have taken some abuse and still more reliable then others? I know these are probably stupid questions but without tearing the motor apart I will not know how they really are. -by the way, I have a YZ250 so I want to add the 4-stroker to my stable.