I am looking to buy a YFZ450. What years had problems? Which ones do I want to avoid? What do I need to look for when I am looking one over(bad stuff) I know to look it over well but if you know of things specificly.
I also Own a 2006 LTR450. Bought it new in 2007. Yep about 60 hrs and tranny problems. Where can I find gears and tranny parts for this bike? Or are these dealer only type Items? All help would be appreciated.

The YFZ came out in '04. The only mechanical difference between the '04 and '05 was a metal plug on the side of the case vs plastic. In '06 yamaha came out with the second generation YFZ that had approx 80 different/upgrades on it. There is a considerable difference in them vs the used prices now. Also, on the '04 and '05 models they tend to have the crank bearings go out early due to a lack of proper oiling. There is a cheap mod that can be done to the side of the case to fix this but usually the 2nd generation quads can be picked up for a few hundred dollars more then the first years. The third generation YFZ has now been out for nearly a year so the first two are getting cheaper each day. $3000 will buy you a great, 2nd generation YFZ.. with extras