I ran 4 tanks thru on the bench for break in adjusting high needle valve as the spec book advised.The first 3 flights/tanks I ran rich.Ambient temp will effect mix as you probably know.The last 3 tanks I have been able to run a few clicks leaner...but still to the rich side.I adjust to lean until rpms begins to sag...back thru high rpm @ 2-3 clicks to rich,with a small decrease in rpm.The "pros" I fly with have always advised to run on the rich side...especially on a new engine.I am fortunate in that I have found a club that has alot of experienced flyers and even though I am 46 they consider me a kid still and watch over us "kids" like grandfathers would.They won't let me burn my new motor up if they can help it.I have learned alot from them in the short time I have been involved in this R/C airplane stuff.(5 mos.)The motor tuning part is harder than the flying part to me.My Super Star/OS .40 LA was used and already broken in....just gas up and go with little/no adjustment.........keep us posted on your progress