Strange issue. I recently rebuilt my petrol taps as they had been leaking a bit. Reinstalled with new corks and gaskets. Now, the right hand tap is fine but the left tap drips, but only if the bike is running. Not sure what to make of that. Planning on removing it and possibly replacing the cork again but wondered if anyone had thoughts on why it would only leak with the engine running.
I make my own corks from synthetic wine bottle corks. Work a treat, don't leak and immune to ethanol and never had to change them after some 10 years on the bike. Cut to shape and make the hole in the middle with a hot needle.