If you still have carbs leaking out the overflow tubes after checking the usual suspects ( float level, split overflow tube, grot in the seat etc) try this.
Remove the float valve assy from the carb, fit the needle valve and slowly invert the float valve assembly. If the needle doesn't slide out easily before you get much past 45 degrees polish the float seat and needle with liquid metal polish and a cotton bud ( Brasso, Silvo or whatever is available in your country) until the needle just flops out easily. This technique has cured my last 3 bikes ( 2 500s and a 550) and is the ONLY thing that cured it.
