Motorcycle Repair: gas coming out the operflow, metal needle, float valve

Question
I have a scooter and the other day it quit running and I noticed a trail of gas behind me.  I pushed it home and took the carburetor bowl off.  I checked the float and everything seemed fine.  I cleaned the metal needle valve to make sure and I could find nothing wrong.  Put it all back together and when I push the ignition switch it won't start.  As soon as I quit pushing the switch gas comes pouring out of the overflow.  Any ideas?

Answer
Check that the scooter has either a manual or vacuum operated fuel tap. Verify that the fuel tap is in the correct position and is operating correctly.

Remove the carburetor and put it on a bench with a small bottle feeding into the fuel line. Verify that the float valve operates correctly and that the float height is set correctly.

I'm guessing the float height is set too high to allow the float valve to close.