I have also done the vent mod & it all went good, Where did you run the carb vent hose to? I ran mine out the right side & straight up into the airbox into the rubber grommet on the right so basically this tube is venting in between the filter & the carby's so it would have a bit of vacuum in this position, Block off any other left over holes in the airbox & plug the tubes coming from under the manifolds/intake after the mod & it should be good?
I cant find the diagram that I used that showed pics of a ZXR not a ZX7 but this one gives you the basic idea>
http://homepage.ntlworld.com/webzxr/.../ventbowl.html
Can you explain where you ran the pipes etc & why it did not work, I imagine it was not running right but what was it doing exactly?