Breather help

[maverickmk]

My understanding is there is pressure created inside the motor from compression and windage and if this pressure is not able to be relieved by a breather, PCV etc then things like the dip stick pop up and oil blows all over the exhaust, weak seals start leaking oil. But, as I think about it there would also a vacuum created by the carb to draw out fumes from the motor to be burned off, so there would be potential of the hose (very thin hose like FO69 said) to collapse or restrict. Also, I could be completely wrong