Update! Sorry it's been so long, but I wanted to let everyone know where we stand. After taking everyone's great advice into account, I went back in and started disassembling. It only took a minute to determine that the choke plunger was stuck!! I lubricated it, worked it back and forth a few times, and whala -- a working choke!! NOW -- while the bike idles nicely when it is first started, once it warms up, it seems to want to race (increase rpm) after 5 to 10 minutes of running. Is this most likely an idle adjustment? Or a mixture adjustment? Any insight would be appreciated. I feel like I'm close to having this thing running right! Thanks everybody

 

All bikes with carbs do this, on cars fitted with SU carbs (the original CD carburettor maker) there was often a little lever on the side of the choke (enrichener) mechanism which set idle speed stop higher while the car was "on choke," to compensate. Set the idle speed to suit a hot engine, if it then stalls when cold and on idle, live with it.

 

If the idle is simply high once warmed up then lower it to were it should be and try it there, expect to need the enrichener for a little more time but once at running temp it should be fine. With your prior sticking enrichener it would not be uncommon to have had it too high before just to keep it running.

If you have a hanging idle ( letting go of the throttle and having it not come all the way down until you put the motor under load or blip it) then you are probably very close to proper idle and the idle again needs to be lowered just a little at a time until it does not hang. Common on non-CV carbs.

If the idle is erratic meaning it is all over the place without you touching anything look for air leaks or fuel getting in that should not.