Joe
As I already said somewhere else.
You either have a cracked ring or here are some others:
Blown or loose Head. Does the head have a copper gasket? Check for loose bolts + check the gasket
Rear crankshaft cover loose..check bolts
Take off the muffler and check for bad or deep scratches on the exhaust port and spatially on the ring. You can see them showing as vertical silver lines. Very fine ones, less then a hair width are normal. Also check the piston for colour. At this early stage, the piston should not be a dark brown. If it is, then you are running the engine too lean.