I forgot to mention that the engine has a Frank Bowman ring as well.

I original design is poor for the ring, as the pin in the piston ring land is the full depth and width of the land, (groove). That makes for a ring with a very large gap. With Frank's Ryobi rings, you either tap or grind the pin down halfway. Then Frank's notched ring fits over the pin, and you have zero, or almost zero ring gap. Helps a lot!

AV8TOR