more comment from down under, running in a ringed engine -- start rich--cool --then its a lot of short runs [on the bench] cool down between , gradually leaning it out till you get to a rich setting on a 2 stroke rpm[all this with carb open full] make sure you have at least 5% castor in fuel. i like to run in my engines on the bench where you can get to them[repeat, lots of short runs--3min ect] then when the engine will hold a full rpm setting [still slightly rich]same condition as nose up climb----go fly.
Ian White Yankalilla Sth Aussie