I've mentioned in a few other threads that besides my normal shirt and tie job I also do all of the carb cleaning work for a local mc shop that subs it out to me. From what I have seen (and corrected) countless times, people will endlessly chase their tail looking for mysterious carb problems when in fact it is, more often than not, a simple case of improperly cleaned carbs.
I've cured dozens of no start, poor idling, backfiring, etc issues using a high-quality, American -made ultrasonic cleaner along with the proper chemicals. The shop keeps sending me all of their carb work because my nearly $1,000 cleaner and $75 per gallon carb cleaning chemical flat out works like nothing else. This week alone, I cured various running issues on a 650 Savage, a 1970 Honda Scrambler, 3 Chinese scooters, and a Generac home generator.
Until you know for an absolute, 100% certainty that your carbs are indeed meticulously clean and thus allowing you to eliminate this as the cause of your fueling issue, you may just end up spending a lot of time and money chasing dead ends. Nothing, absolutely nothing, can clean all of the carb circuits (especially the tiny idle and low speed circuits) like a quality ultrasonic cleaner (and not a $59 Harbor freight jewelry cleaner) and dedicated, cleaning chemicals specifically formulated for carbs. A $25 one gallon dip tank from PepBoys or a can of spray carb cleaner are not going to get the job done. Spending the money upfront for this service is money well spent.
If you haven't sorted out the issues, try to find a local vintage car/mc shop that offers this service. If you do, ask to see the sonic cleaner so you can verify it's not a Harbor freight (or similar) toy; a lot of people offer this service but in my experience, either out of ignorance or malfeasance, they purchase cheap, low-end cleaners and use basic cleaning supplies such as Simple Green. The real shellac-dissolving chemicals cost much more than Simple Green for a reason... Good luck.
