From The Top.

Took her out for a nice long ride today. As I was almost home I could feel a slight miss. I pulled the plugs and wouldn't you know it Black, and Sooty again. SO I said screw it "I'll throw on the coils mod to see what happens." I did this and wouldn't you know it after a short ride black and sooty. So far I'm over $500 deep in parts. Think I'm going to cut my loses and park the it.

Understandable why frustrating but take a break a couple days or so and get back at it for your closer then ever....

You have your electrical to spec right...?
This time you got 30 miles versus 15miles before sooted on you...

Assumption is all 4 plugs sooted or just 1/2 of them...
Which plugs 1/4 or 2/3 or all 4...

Whats the common variables between all 4 plugs...
Electrical, yup...
Coils are matched...
points and condensers or EI... matched 1/4 & 2/3....
Carb choke circuit...
etc....

Had this worked previously, no issues and now all of a sudden... Again, what's the common factor is t-shooting the possibilities...

Possibly you have an intermittent electrical failure occurring where Dyno/Rectifier/Regulator is failing.... As previously provided, you did go through the whole process correct?

Clean the plugs, make a voltage measurement (no coil mod) and @ 4Krpm, ~ 13.5Vdc?

Take your meter with you, go for a ride... When you notice it "missing", pull over and re-measure... Electrical mentioned components may be breaking down in loaded operations thus heat...

As Tim and others have mentioned from the beginning you may still have carb issues to contend with and carb sync...

Then there's where are the valve clearances, ignition timing and possibly timing advancer to confirm/repair...

This is ~ a 30 year old motorcycle right... Hell, me as well as others took 2 years to get dialed in... Sure we did some other things that added to the time frame to completion but had to go through the same poo-poo your going through....

Take a breather, do your research, study the manual for all possibilities, go through everything that has been provided, and when you're ready to jump back in... Attack it, double check/confirm/measure ...

As mentioned, hell we've all been there ready to take a match to her... :blink: Here that'll fix the carb problem.... But keep at her when you're up to it, you're making progress and probably closer to the repair then you may realize....

OMR

could be oil is getting in there, fouling the plugs, it's an old bike, (like mine). If you are going to let it set for a while, get the head redone.

Try a simple but as yet proferred tip:check the plug gaps.if they are set at factory spec(.032mm) regap them to .040mm reinstall,take a long ride and run the crap outta it.bj

If valve clearances haven't yet been checked and assured within specs, then BOO on You! :kiss:

Good Fortune!