When starting in colder weather I have the enricher/choke on the highest setting. Almost immediately after starting I start backing off the enricher. Somewhere in the middle of the range is where I have it idling (unassisted) the longest. Eventually I back it all the way down and give it some throttle until it idles comfortably by itself. I'll wait until the headers are warm to the touch, if not already, before taking off. Total duration = 5-6 minutes. How long is the duration from full enricher to no enricher for you?