Blue hose from carburetor?

[AlexT]

Can anyone identify the hose in the attached picture? I was adjusting my clutch cable when I see it hanging down. It disappears up between the carbs and the engine. I see a few hoses marked in my manual but I can't tell which one this would be and if it is supposed to be attached to something on both ends.

[X-ray]

Possibly the drain from around the fuel cap. The nipple is on the bottom whip a solid metal tube goes through the tank itself.

[Slack]

take your seat and tank off and follow it.