I ran about 1-1/2 tanks of fuel through mine before I placed the cowl on. I did have to do a bit of adjustment from the factory settings, after it was warmed up. On the low setting I'm about just a hair under one full turn out. and the high end setting is about 1-1/4 turns out. Good transition, no burbling at mid to low rpm and a good idle. Maidened with the cowl on and haven't touch the mixture screws since. Mike (ACF)