Just finished a complete top end rebuild. New cam chain, cylinder, gaskets, piston! This was all due to an anomalous noise that started at random on my 07 YZ450 that I bought used. Bike had 22 hours on it when I bought it and at 36 hours the abnormal noise started (clunking..clicky..almost rattly noise). Well I finish the rebuild today (even after my first parts package from Rocky Mountain ATV/MX fell off the UPS truck and a landscaper decided to keep for himself a week ago..another story) and started the bike up for a phase 1 break in run and wouldn’t you know the same noise that was positively identified as piston noise by a "mechanic" previously prior to the rebuild was still very audible. So it looks like a complete bottom end tear down and rebuild is needed. I’m not comfortable with that level of maintenance and now don’t have the disposable funds to even attempt it after dumping money into a fresh top end (which it did need also). Just a huge let down after putting in all the time and effort into removing the motor, cleaning, rebuilding, installing, and now no pay off. I feel like trying to save money by doing the work myself has not paid off. Just wanted to rant. P.S. to Jose Martinez in Rialto, CA, I hope you have fun with my $400 worth of YZ parts that “fell off the UPS truck”.