As far as I understood, it enrichens the mix during decceleration with throttle closed, right?? If so, is there a chance it keeps doing it after  stopped?? My bike started acting really funny, rpm start dropping on idle and black smoke starts coming out of the exhaust. Rev over 2500rpm - no smoke. Same thing happens in the morning, I crank up with choke, push the choke in and in few seconds it starts sputtering with smoke, and dies. It cranks back up easily, but it started to piss me off. Even with normal idle set to 2000rpm, it still does it. There's times when everything is normal, can't relate to any pattern of weather, temperature, or such.
150 main, 50 idle, needle one slot up, K&N cone, HD open exhaust.
Sticky slide or... Transient? Enrichment?

So the logic is that extra fuel gets drawn through the vaccum line? Might be. I will test that today and repost.