1999 bayou 220. Died won't start. Has spark, air and fuel. Only has 30 psi compression. How do I detrtmine if it's the rings or valves? Wasn't using oil or smoking before it died. It was making kind of a top end rattling noise for awhile before it quit.

 

You would need a leak down tester, basically blow compressed air in through plug hole, and listen for air leaking out through exhaust and carb, if it isn't leaking there it must be head gasket or rings, probably hear that too, but who cares? Re set valve clearances and, if that doesn't fix it, the head has to come off, so check the valve seats, gasket, bore and rings and you will find the problem that way.