I'm 16 and im looking for something to ride the trails with, im looking for something low maintenance something that i wont have to change the piston/rings every 50 hours, looking for something not that old 2004 and above in the 3000$ area, i had a 400ex in mind but was not to sure, is it hard to find parts for quads like the 400ex 05 ( or newer) like oil filters pistons/rings,clutch.

 

Really any 400 is low maintenance. I had a 400ex for a while and had no problems at all, but they are kinda slow. They are very easy to find parts for too. Aso, the kfx 400 or dvx 400, or z400; they're all the same bike with the same motor. So lots of parts there. Frankly, Honda's probly gonna be your most reliable bike.