At idle, only the pilot circuit should be active; assume you cleaned that out well, and that you have adjusted the pilot screw properly.
Air leak from the intake plumbing?
I'd add, "Carburetor diaphragm properly sealed," except--I don't think the diaphragm plays a role at idle.
Not likely the "choke" (starting enricher). When closed, no fuel nor air enters the venturi from this source, except--can't certify the aftermarket "choke" on your bike. The plunger must fit properly, exactly like the OEM part, to insure correct operation.
Wish, I could be more helpful; I'd start with the fuel screw adjustment, once I was convinced the aftermarket choke was o.k. (e.g., plunger profile and excursion range correct, cable attachment cap intact).
Last edited by Damocles; 11-21-2013 at 06:11 PM.