sure, but why buy a new carb when all you need
is potentially a good cleaning of the old one, maybe a readjustment of the floats?
Yes, you might need to get a new needle valve, maybe the floats...
but if you are at that point you can still always buy a new carb, no?
Non vented tanks can cause carb spillage!
(cold air in tank expanding when heated up forcing fuel into the carb...)
a vented cap will certainly solve one of the issues you are having!
(if the tank has an internal ventilation then it's certainly easier to clean that out properly)
if you simply ignore that tank ventialation issue the new carb will ALWAYS cause problems as well.
Her's a thing for you to test:
get a clean cotton cloth,
remove the tank cap and cover the inlet with the clean cloth and some rubber bands
(you do not want dirt in the tank..)
Now ride around and see if your enginestill dies?
it doesn't? see you need tank ventilation.
Chances are the carb won't even leak as much if put away
(still without cap but just cloth covered)
Now, explain again why you think tank ventilation is not needed?
and remember: tank ventilation has NOTHING to do with how much air the carb gets.
'sid