kz 750 rebuild

I have just completed the long task of completely rebuilding my Kawasaki 750 LTD engine. Almost everything new. I bored it out to 813 cc with a Wiseco piston kit. New clutch, shiny nuts and bolts and a complete valve job. This bike is in mint condition. I drove it out of the showroom in June of 1980. It starts and runs but not well at all. I can't figure out if it is carburation or timing. When installing the cam's I was very careful to line the chain with the cams with the correct amount of links in between 45-46. It looked just like the picture in the manual. I set the 4 idle adjustment pilot screws to the bottom then came up 2 1/2 turns. I have run the bike about 5 miles. I can't get it to idle smootly. When going down the road it seems to have some power but I am not pushing it. It is softly backfiring as I go.  From here on I have reached my highest level of incompetence. Is there anyone who can help me from here.   thanks

Did you rejet the carbs to work with pods?  Perform a vacuum sync?

Hi Ed, thanks for the reply.
I did re-jet the carbs for the pods and the header years ago. During the rebuild I went up one size to compensate for the increased piston size. I do not have the facilities' or have even heard of a vacuum sync. could that be it?