Hi dale,there is a fine line with rich and lean with my engine. I've set it at optimum then backed off a couple clicks and it absolutly screams but just on the rich side. Now when it goes in the air at this setting it will richen up even more and start to slow and fly like a dog. So then I lean it out a little more ,say a couple clicks and it's screaming again(on the ground) with nose up and down. I take off like a banshee and go for maybe 30 to 45 seconds and it seems like it overheats and almost dies to where I have to pull throttle back for a little while to straighten it out. I do this routine all day messing with low needle and high needle settings. It's a bummer because I know this is a high power engine with great potential. I will try a different carb before I call it quits.