Petrol leaks

Had a petrol leak from the right hand carb, and then as soon as that was fixed, the same problem on the left (suspect the balancer hose increased the right carb pressure when the left one was fixed). Once the fuel tap was on petrol was just draining straight out of the overflow.

I removed the float bowl, tapped the float pivot bar out with a micro screwdriver and removed the floats. Removed the float valve next and found out covered in sticky gunk and grit (I suspect that it's old fuel that was left standing) on the valve and in its seat. Cleaned the valve and used some 2000 grit to de-gunk the hole so the valve runs smoothly again. Reassembled, problem solved.

Exact same problem with the other carb fixed the same.