I have had my gs500e for about a year without any problems (apart from having the clutch pushrod seal replaced) and I love it - what a brilliant bike! But recently I have had some fuel starvation type problems couple of times. Then I was recharging the battery and I noticed the carb air vent pipe was trapped between the battery and battery housing! So I pulled it out. Then noticed if I block the hose end with my finger it causes the bike to splutter and stall. So... my question is, what does the carb air vent hose actually do? And why does it cause a problem if its pinched or blocked?

could you point out on a picture which carb port you are blocking?
use digram parts pictures like cmsnl
i suppose you are not letting the diaphragms open so the slides are not coming up.

the carb vent hose is important if you have it facing the wrong way it will stall the bike while riding. Check the factory manual, it has the routing of all hoses and cables.

The vent ensures fuel can enter the bowls

just realized....i dont have any vent hose connected, should i route them towards tthe air filter?

yeah, it goes backwards form the little T piece

nice  the problem is i am missing the T piece, so two hoses will be