How many miles do you guys usually get out a tank of gas?

It all depends on what type of riding that you do. During a race I will get just over 10 mpg. A 30 mile race the tank is empty. When we went to Col this summer and went slow I got between 20 to 25 mpg with the same 400EX. It all depends on the right hand and how fast that you go. Also, don't forgot the mods that the person will make to the quad. Play riding I would guess for and average of about 17 mpg.

Sorry I cant help you on the miles per gallon, but when I'd go ridin with my buddies with my all stock 400EX, I'd get an easy 5-7 hours riding before even thinking about checking the gas tank. When we went up to marienville trails racing around(like cross country)I could go the whole day with it and that was some rough riding.