Motorcycle Repair: carb problems, harley engine, indian scout

Question
QUESTION: Hey Mike! I have a 88ci S&S engine with a super e carb. i know you said you only know about harleys but this is pretty much a copy of a harley engine from what ive been told. its the stock engine on a 01 indian scout. the the engine was lurching with an occasional backfire on low to mid rpm range but full throttle operation was perfect. then it just didnt work. now i have it on the stand and after some carb cleaning and adjustments it will run smoothly on all rpm ranges for 30-75 seconds then it will just shut off with no stumbling or backfiring. if i try to start it again it wont fire at all until i wait at least a few minuets. i put new plugs on,changed the fuel filter, checked for spark and did a static timing check and all checks came out ok. do you think it could be something other than the carb? maybe the coil malfunctioning? i would appreciate any advice you could give.
  also thank you for your service, i have used your previously answered questions and answers to solve a few problems aready. great work!

ANSWER: Pull your plugs and let me know what color they are. Also, check you fuel line and make sure you have a good flow to the carb
Mike

---------- FOLLOW-UP ----------

QUESTION: i was running some autolites and the rear cylinder was just slightly sooty and the front was moderately sooty after running for only a minute or two. i switched to a new set of champions and the front and rear both have the same but less of of it. just a very slight residue. fuel flow to the carb is excellent.

Answer
Your plugs are fouling so it can be a couple of things. I would doa  OHMs test on the coil and plug wires to make sure they are good and within limits. If they are not then replace them as a weak coil or plug wires will cause fouling.
Good luck and happy riding
Mike