[redyaris]

Varn
You may in fact be right about the main jet not being involved, because the CB250 slow speed jet is a #35 and the VT500 slow speed jet is a #38. I suspect however that both circuits are partly at work delivering fuel; mostly as you suggest from the slow speed jet. Changing the slow speed jet to a #35 may be something I have to try.
With respect to engineers; my friend started as a heavy duty mechanic for many years and knows both ends of the process. In fact he intimidates many of his younger coleges with his knowlege of the practical and the theoretical side of things. both my daughter and son in law are chemical engineers and are very helpful in getting my understanding of issues clear even if they know little about the details I am working on. Engineers like mechanics and others come in the full range of compitance...