that hose is a breather/overflow for the bowl or the carb. Pull the carb apart and clean it as best as you possible can. If you acces to a sonic clean, tht would be your best solution for cleaning the carb. Do not get cleaner on the neddle jet. Pull it out before you start cleaning. The neddle valve could be sticking on its seat or one of the floats has failed and fuel is leaking into it. Or it could be that it’s time for a new neddle jet.
Where did you move from and how big of a main jet to you have in?
LAD Specialties customer / tony kart / rotax / kt100