armody- what the "leaning out" advice you are hearing really means is setting the engine mix to the proper ratio for best horsepower. Glow engines need to run rich for break in so that they don't overheat or wear excessively before the parts burnish themselves together. Once that process is complete though, there is no reason to keep running rich. It wastes fuel, hurts your throttle response, and cuts horsepower. Most guys will run their engines a few clicks rich in order to avoid an over lean condition.

joco1- 3 to 1 odds you're too lean. Use the #8 plug (what the engine was designed for) and tune it so you get an obvious increase in RPM when you pinch the fuel line at WOT, then tune the bottom so that it idles and transitions well. After about 15 tanks of fuel, go to the HSN setting that gives you just a slight increase in RPM when you pinch.