The last time I cleaned my air filter I took the lid completely off of the quad and there's this little 'tube' type thing next to the big air hole. What is that? Does it need to be hooked up to something ? It kinda looks like a spark plug cap or rubber 'tobacco' bowl. Anybody notice this thing yet.

 

This is your crankcase breather tube. Leave it hooked up. Probably best to put some sort of a in-line filter in it though, as dirt has been known to get through into the motor.