hey Yamaha guys!! I am a CRF 450 riding who is sick of the Valve issused with this damn bike, my buddy has a 98 YZ 400, the original thumper and loves it.. so I am tossed up between getting a XR 650, and a WR450... few Q's... I know the yamis have the 5 valves, whats the benifits?? valve life, and we talking a entire new valve system and re cut valve seats every 50 or 100 hours like the CRF? or do the WRs hold up? or is it luck? some guys have the problems, and some dont? what are some Years to avoid? what is the 1st year of the WR 450? i am currently looking at a 2003.. thanks for any advice!!