Me too, I quit filling at the pump early on - too much commotion causes spills ect. Bought a good gas can and do it at home on all three bikes. Use a flash light to keep an eye on filling....
I had a vacuum forming in my LIKE tank. Removed all the vent hoses & valves and cleaned/blew/dried them out. No more issues after I reinstalled everything.
Stig
I find it hard to believe that our scoots are that sensitive to a bit of over filling - these things are sold 'round the globe - and there are guys filling these scoots in the pouring Amizonian rains by candle light with an old Pepsi can....and they still run just fine on market days.
I think.
I believe any imagined issues I thought I had were solved by cleaning the innards of my gas cap. I blew into it, sucked it, rapped it, washed it and generally abused it significantly until it began to properly vent the tank again. In or out, I don't know....but vent it it did. Hopefully it was supposed to.
And I had no more noisy air movement when opening the gas cap. (My "presenting symptom".)
Still, probably not a good idea to over-flow the old gas tank on these rascals.
OK, that's all I got. I'm outta here!
Stig