Can you take a photo and show us what you mean? You will probably need to borrow a sync screw tool to get at them. You also need a set of sync gauges to get the sync correct.
This carb(not fzr) sync screw is facing upward then in our carb fzr looks like this facing downward(this is my spare carb)
Yeah my 3LN3 carbs have the centre screw acessed from the top and the one's between 1/2 and 3/4 are accessed from the back behind the bottom of the fuel bowls between 1/2 and 3/4. All are easy to get to and adjust. I synced mine on the bench first with a piece of wire, but then synced them again with my Carbtune balancer, it made a lot of difference after doing them again on the engine. .
