Fuel line

Hi guys, 


recentely I started to rebuild a vespa PK 50 xl plurimatic.


After a proper engine overhaul and a new paint job, I started to rebuild the little wasp. Well, now I got one question for you.

Because I bought the vespa allready dissasembled, there are some parts that I'm drawing a blank on where to put them.

And this is the big one (dutch scooter forums haven't helped me so far...):

On my engine, there is a fuel line that goes from the fueltank to the carburateur. But there is also an extra line connected to the inlet of the engine. Here is a picture so you know which fuel line I mean:


Does Anyone know where to connect it to?