Avg Miles for a KDX

Things I look for in a used bike. Get the bike up on a bikestand. Check for lateral movement in the swingarm and rear wheel if play exists then the bearings are shot. Next I check to see if the front and rear suspension move up and down freely, Rear more so than the front because it probably means that the previous owner did not take the time to properly grease the linkage,swingarm and shock bearings. Make sure the front turns freely, same thing grease on the bearings. I don't usually judge a bike by tires, chain, sprokets, breakpads unless they have gouged into the rotors. Stuff like that most people are likely to change anyway to suit thier style of riding or type of terrain. Also don't be afraid of a bike if it has been raced. A real racer maintains thier bike probably better than the ones who "just ride around the farm" I know I hate breaking down in a race. You can usually tell quickly just by looking at the bike if it has been taken care of. Other things make sure it runs, starts easy, take it for a ride make sure the bike goes through all of the gears smoothly and without any strange noises. It is hard to tell how many hours or miles are on a bike. Some people can trash a bike in one day and some can ride a bike for over a decade and it still looks new.
Finally if you dont feel comfortable judging a bike take someone along with you that is.