I would break-in the engine on one of your cool engine test stands you make with a 10X6 or 9X8 prop on 10%. Add a tablespoon of caster oil for a 8oz tank. About 3 tanks should do it. Let it cool down completely between runs. Don't let it run too rich! Let it scream about 600 rpm off peak, slightly rich two stroke. Before you start it, put about 4 drops of fuel in the glow plug hole, put the plug back in and turn it over by hand a few times. On new squeaky tight engines on cold days I like to turn the piston to the bottom of the stroke and warm the head (carefully) with few passes of a propane torch just before I start it (first run only).
Too rich (cold) and you hurt the connecting rod. Too lean and you hurt the piston (the pinch at the top of stroke goes away). While it's running, if you can hold your fingers on the head for more than a 3 seconds it's too rich. I guess it depends how tuff your skin is
