Instead of trusting the plug color with today's crappy gasoline and many carb circuits in play, remove a shim and ride the bike through a tankful. Keep removing shims (or lowering the needle .020 at a time) until she stumbles around 3-5K on cruise. Then, add 1 shim. You're done.
This was the Dale Walker method of old and very effective.
Marc/Atlanta
'99 B12
2" Crazy Ed mod, Dale needles.