I own (2) 4-stroke quads and was wondering how to read the plugs? They are both totally stock!!!!!!!!!! Whats a normal color for the plug after say a year? And what does each color other than normal mean? Thanks Alot

white is lean (bad) meaning you need bigger jets,black is rich meaning smaller. you should be changing the oil,plugs,filter every third trip out. if you think thats too much $$$, check out what a new motor cost.

Michael is right about the plugs but I would switch his times up a bit on the other maintainance items. Airfilter (Not sure if he meant air or oil) cleaned after very trip. Sand will work its way through your filter and really takes a toll on the cylinder/piston when it does. While you can't keep all sand/dirt out of your motor, cleaning the filter after every trip keeps it to a minimum.
Depending on your bike, oil should be changed every trip to every few trips. The raptor and 400ex could use new oil after every three or four trips. Higher performance bikes like the KTM two wheelers don't hold alot of oil for weight reasons and need to be changed every trip. My YZ400's oil gets changed every two trips and the oil filter gets changed every other oil change as per Yamaha.
Plugs are debatable. I change my thumper plug out once a year and the plugs on my banshee out every couple of years. Changing em out every three trips is a bit excessive in my book when those suckers cost so much.