got an 03 banshee that wont stay running. its hard to start but once you get it goin it runs great for about 5 minutes then it starts spittin and sputterin then dies. it has new piston and rings, crankshaft, all seal , ignition coil, reeds, plugs. ive checked the petcock, jets, floats, all boots and gaskets, has spark, cleaned carbs and tank, runnin with new 93 gas mixed 40:1 checked choke tube TORS disconnected. what could it be?