Okay so I am confused. Where does this hose go and what is it. Is it a pcv valve or a crank case ven. Where does the hose need to go? Can it vent into the atmosphere? I deleted the air box on this 150cc gy6 engine. Any clue?

 

A PCV valve is crankcase ventilation. The pipe should, by US law, go to the air filter so fumes go into the engine to be burnt, but won't affect performance to just vent to atmosphere. However deleting the air box may not be a good idea on a quad, you can see the dirt caked on the engine, some will be sucked into the air intake too, unless you have fitted some alternative filter.

 

Yeah I put a pod filter on it. It's just for my kids so it's not gonna be getting to messy. The old air box is weird it has a hole in the top of it. I tried to find a replacement box but none matched up perfectly.