I just bought my kids a used 50 cc Chinese ATV by Fuxin and I noticed this hose with a plastic piece laying in the frame and the one end of the plastic piece (nipple) wasn't attached to anything. Anyone know what it attaches too and what it is?

 

Looks kinda like the one on mine. Mine hooks to the opposite end of the air filter. Opposite of the carb but I'm no expert by far.