Apollo 250 AGB-36C Assembly Questions

[MudIntent]

Hi! I recently joined this forum and wanted to introduce myself and ask a few questions regarding the assembly of my newest Chinese bike an Apollo AGB-36C.

I found this black device hooked up to a hose under the bike, but the end that's not attached to the hose isn't connected to anythjng. It was just hanging like this under the bike. Looking at the pictures I have uploaded, I also found this other piece of tubing that has a plug in it and I was wondering if this could be where the other end of the black cylindrical device plugs into, or if it is supposed to be like this. I have included some views of the specific engine that is on mine as well as a picture of the entire bike. Could someone please help me understand what this is? Thanks