Motorcycle Repair: 1991 HD New Ignition, Still fouling plugs, weather ranges, screaming eagle

Question
Hi Johnny...  Here we go again...  1991 HD Fat Boy, 1340, supertraps...  With the spitting and sputtering fouling out plugs routine...  Originally a CA ordered bike, now in the Midwest.  

With the old ignition, it was primarily fouling out the rear plug (black and powdery), whereas now with the new ignition system, it is both plugs fouling out, black and wet...

Installed the new (new) Elite 1 (242319) ignition module after the manufacturer replaced the defective one, along with the BPR 8ES plugs.  The bike purred like a kitten.  

For about 2 hours; (idle was excellent, put about 100 Highway miles on it).  He also mentions that there is a subtle loss of power...  

Then it started fouling out plugs again.  

If we clean the plugs and reinstall, purrs like a kitten for about 4 miles of riding, then it starts to spit and sputter again.

We've also got a set of the screaming eagle plugs, and it seems to run for longer with those than with the NGK's.

Kind of a two parter...  The "choke" knob:  our weather ranges from 70's during the day to mid to low 60's at night...  What should the "choke" protocol be?  

And, when he uses the choke, the bike runs fine, but when you open up the throttle, the choke knob will suck itself back in, and the bike starts the spit/sputter routine...  Should this knob stay where he puts it, or is it supposed to suck itself back in?

The fouling plugs problem happens no matter what he does with the "choke"...  If he doesn't touch it, we get 4 miles.  If he adjusts it, we get 4 miles...  

When the bike was in the HD dealer shop in June, they did put new jets in the carb...  But, nothing has been touched with the carb since that point. (no Dyno)

We've got a side issue with no close by Dyno mechanic, the nearest one that has come recommended to us is 90 miles.  

Quite simply, whatcha think?  

Thank you so much for the time and effort you put into this.  Mon ami, merci.

Answer
you did not tell me what carb is on the bike???. if carb spits back it is a lean condition. You need to do a compression check and a Leak down test to see where the motor is at. the choke should not pull in by it self. you do not have the choke backing nut tight enought or it is broken, use choke just to start bike then raise idle to 1,500 rpm and tak choke off and let it idle fast untill heads start to get warn then lower idle back to 1,000 rpms.  Call if you like 602-705-7474  Johnny