650 speed demon?

ive done everything bg has told me to do,timing ,floats,butterflies and fuel pressure,still running rich at idle.Turns the plugs black, if i can get the idle leaned out id be pleased,everything else is fine.I know the mighty demons come with idle restrictors in brass but a speed demon just comes with holes in the aluminum.I seen on a site where they drilled holes in the butterflies or drilled out the 4 air holes in the venturi,any ideas appreciated


thanks