I haven't done any test of valve, anyway the scooter was starting OK few months ago, there was just a "small problem" with electricity, it was not recharging the battery...
And now, after I've checked all the electricity, replaced some components, it doesn't start... Can it be sth like overfull because of many attempts to start it? Something like too much fuel sucked in the engine?
I tried today to check the tube from fuel tank to the engine over carburator, if it cannot be clogged, but it seems to be ok, at least the filder filter just below the tank.