Along with the mid-RPM flat spot on my 84 VF1000F, it seems to vibrate a lot. I have a 99 VF750 and it acceletates harder and does not vibrate much at all. What if any effect would the cross tubes between carbs have if the O-rings were bad? If one carb was gunky, leaning one cylinder, would that cause vibration? It doesn't seem to be missing, it just seems choked.
If the O-rings were bad, you've have gas leaking. A carb sync can remove vibration. To determine which carb circuit is causing your flat spot, you need to read the links at the bottom of this page: <http://wiki.sabmagfaq.org/Carburetors/Tuning>
just a thought I would suggest pulling the carbs off and cleaning them and sync . I never look foward to this but it is best to just do it and get it over with. If that does not cure your problem then those a two chores behind you that can be eliminated and not a total:thumbsup: waste of time as good maintenance as well.
