wont start and petrol leaking from overflow tube

[Fazerider]

You can identify which carb is overfilling by checking the fuel level in each.
You need a short length of polyethylene tubing that fits on the drain spigot at the bottom of the carb. Bend it into a “U” and slacken off the drain screw and watch for the level the petrol rises to compared with the seam at the top of the float bowl. Details in the manual.