If the bike isn't making any funny sounds, the just run it. I'm closing in on my 6000 mile mark with no problems at all. I'm sure that the cam chain might need to be replaced at 15 or 20 thousand miles, but I'm not touching it till I hear it rattling.
The DRZ is a driver bike with very little to fix. Some folks have had the carb gumming up because of old gas. Other then that, it is one tuff cookie !!!
From jeathrow Bowdean