Modern Vespa

Hello All,
I replaced the fuel Tap and replaced the needle valve in the Keihin Carburator. The new fuel tap shuts off when not running.
When i take the scooter out for a ride then park it a little while goes by and fuel leaks from the lower small outlet at the base of the air filter housing.
That outlet is open and does not have a bulb on it. What else could it be?
Any help is appreciated.

Did you replace the "fuel tap" with an OEM vacuum-activated petcock?

If more than a shot glass or two of fuel is leaking, then the petcock is not closing, AND the needle valve is not sealing.

If less than a shot is leaking then it could just be the needle valve.

The fuel Tap is an original Piaggio Part and it's turning off when the scooter is not running.
The needle van is brand new.

If you're sure that the vacuum valve is working in the petcock then what you're seeing is probably fuel draining from the petcock valve downstream through the needle valve. The needle valve could be seated incorrectly, the lever that establishes the float's level inside the bowl might have gotten bent, etc.

There "should" be a little clear plastic bulb capping the drain in the airbox, but that's primarily for small quantities of oil that can accumulate there from blowby and from excess oil in the foam air filter. Many scooter designs don't have that bulb at all, and let whatever builds up there drip onto the pavement.