fuel shut off valve was not letting enough gas pass thru.flow was too slow to keep carb full.

 

I'm thinking your post is in response to this thread?:

http://forums.atvconnection.com/chin...nk-atvs-2.html

I've had experience with two quads that were not passing enough fuel through the fuel shutoff valve to keep the carburetor full. The symptoms were easy starting, normal operation for a couple minutes, then the quad sputters, coughs, and dies. When you crank it immediately it won't start, but if you wait 30 seconds it starts right up and runs for 30 seconds. Then it sputters, coughs and dies.....

Quad one had a molding problem in the rotating plastic shutoff ball in the valve that was blocking fuel. I drilled the molding defect out.

Quad two had a 1/4 inch *water* shutoff valve installed which was bought at the local plumbing supply store. Over time the neoprene gasket in the valve swelled up from exposure to gasoline and blocked the fuel path. I replaced it with a valve designed for gasoline use.