Thanks Batman.  The yellow hose you see is the vacuum hose not a fuel outlet.  The black hose you see at five o' clock is the fuel outlet.  

Any differences in hose clamp size are merely an optical illusion, where the camera lens is closer to the vacuum valve and further away from the hose clamp in question.

This setup has been in service for years, ever since I read that a forum members crankcase got flooded with gas after forgetting to shut off the fuel valve.  The float in the carb had got stuck open for some period of time.

In fact the idea was inspired by someone on this forum.