Originally Posted by
Flypaper 2
Lean it out to max rpms then back off until just before it starts to stutter from being rich.
That's for glow engines. I've never tuned a gas engine that way. I've done it like this for years...after running a 1/2 gallon through it, run it at WOT, kill engine while holding WOT, bring it in, pull the plug and check the color of the insulator, richen or lean it from there, repeat procedure until the plug is a medium brown color. Done.