I think that I got the after fire issue fixed!
I went to my local carb shop and purchased a used spring from a Rochester 2BBL accelerator pump (see image)
The dimensions are the same but the wire diameter is different.
The original is .036 while the Rochester spring is only .025 making for less compressed tension.
The removal and replacement took much less time than driving to the carb shop.
I made several runs through the gears getting on and off the gas as hard as I could and I could not make it back-fire! I stopped several times, blipping the gas and shutting it off; but I could not induce the little burp we know so well.
The intake and exhaust on my bike are heavily modified, so I can't say that this spring will fix a stock bike...but I have a plan!! There are a couple of other riders here in Phoenix that I believe are riding stock machines. I will attempt to locate one of them and offer to “Fix”his bike for free ($2.00) and report back.
Once again...Thank you all for your help and support.
JB