I had my MVVS 45 quit running while in the air on a maiden flight, got the bird down for a nice landing.. Checked things over to find out why the engine died and couldnt find anything. At home I pulled the cylinder head to find a broken ring. Also in the exhaust port the vertical web had a bit of "slag" remaining from manufacter process. At that spot there is a void in the piston top down to the ring groove, I believe this to have torqued the ring causing it to break.
Sad part of this is I traded for this engine so I do not have a warranty. I believe the cylinder to be useable, have one super tiny mark that I can just barely feel with my fingernail length of the wall vertically, but I feel it is so small it will not pose any problems. However the ring and piston are toast.

Greg,
Can you make a detail picture of the ring and piston? It looks like a piece of the ring damaged the piston.
MVVS cylinders are ground, not honed, so you just need a new ring. If the bottom ring land has no damage the piston probably can be used as is.

Here is the pic.

looks like the piston lives another day.
Rings break. Yours is not the first, nor will it be the last.
I suspect a small piece of the broken ring, or maybe foreign matter from the exhaust to have caused the damage on top of the ring groove. Since gas pressure or momentum tend to press the ring down all the time, this will not impair operation.
Check the ring groove bottom for damage. The old broken ring is a good tool. Fit a new ring and you will be fine. Use more oil for the first gallon (~4%), and go easy on the throttle until things have seated again.