I think the problem is likely the cheap, hard rings. In the old days of full scale radial cylinder engines, the rings were broken in on the bench by coating the cylinder with fine grit lapping compound and manually running the piston in and out for awhile. The mess was cleaned up and the rings were broken in. I am tempted to give it a try just to see what happens. It is not like I am using expensive engines, most of them I buy at garage sales for under $5. Next time I go to town I will try to pick up some lapping compound and give it a try. Half the hobby is trying new things, and sometime the new things are a disaster!