LOOKING FORWARD:
Though giving it our best shot, be prepared to further "fine tune" your carbs, Bob as we are not likely to "nail it" immediately on the 1st try.
Black spark plugs and failure to accept throttle was, no doubt, influenced by the high fuel level due to the defective float valve. Off idle, open throttle plates and rising slides did not supply correct fuel curve. I'll contend the most affecting factor is at
the beginning of needle rise .....not at the end, which is more affected by the main jet size (which still may require further tweaking).
I repeat, be prepared for further fine tuning "down the road".
For now, I'll contend adding 2 needle shims is called for at minimum. In conjunction with smaller mains? I'd strongly suggest making just 1 change at a time.
As it IS your bike, I'm open to discuss before reaching a final conclusion on which way to go...shimming or mains, pilots or some combination thereof.
I'm awaiting a jetsrus order reupping my stock of varius mains and pilots, should be here by Friday or Saturday.
In the interim, I suggest giving this thread a close read:
https://www.ninjette.org/forums/show...tting+database
concentrating on '08 and up comments (dismiss early gen and any with "pods, no airbox" )
I'll further comment your bike (with altered exhaust) was never fine tuned from PO to you as jetting is still in stock state. Time to hone in on it!