I have been messing with this for two weeks now and need help.....
Details: 1995 Springer Softail, Stock Engine, Thunderheader, K&N round filter.

Running really rich at idle and really lean in the mid range. Plugs are black except for the porcelain and the electrode tip. Those are white/ grey and the rear cylinder has white particles on it. (Lean) This set of plugs has only about 50 miles on it.

Details.....
CV40 Carb
46 Slow Needle - Air screw 2.5-3 turns out
170 High Speed jet
CVP Needle - no washers...
New Harley Vacuum Piston
New CVP Spring
New CVP Needle Holder
New Harley Emulsion tube
New fuel needle

Checked for air leaks with wd-40, non found - ruled that out...
Enricher is closing, and hasn't been used to start, I just hold the throttle until idle comes up or take off right away.

Bike runs pretty good especially on the top end but exhaust is solid black on the inside and it smells rich....

 

Check the gasket where the carb slips on to the intake manifold, these can develop cracks over time.

 

That has been replaced. I am going to replace the intake manifold gasket just to rule them out.