Guys

I have a problem with fuel overflowing from one of the carbs. So far I have

Flushed the tank/replaced the filter
Replaced the float needle valves
Adjusted float heights

All seems OK but after a while, engine running or not, fuel comes from the overflow. I swapped the floats themselves and hey presto, the other carb flows fuel from the overflow pipe in exactly the same way. Before I embark on replacing (both sets of floats) do they become porous as I think this is the problem.

Thanx in advance

Phil M