I'm beginning to think those "needle valves" should be replaced at a regular interval of, say, every year or two. Not too long ago I disassembled 5 valvesasiab3 wrote: There is also a new needle valve in the carb.
I happened to have, and found: one, probably from some rebuild kit, had a ball bearing tip instead of a needle; one with non-Solex markings, but otherwise
of identical construction, in good shape; and three Solex valves with a very pronounced wear ring where the "needle" met the seat.
The "needle" is actually an approx. 60 deg. cone that seats on a fairly narrow chamfer at the valve orifice.
While those worn valves probably do an OK job of regulating fuel bowl level underway, they may well leak enough at hot shutdown or when subjected to
fuel tank gravity pressure to cause problems.