I use a three line fuel tank system for all my gas engines. One with a felt filtered clunk as the feed line to the carb, one with a regular clunk as a fill line and a vent line. Some folks use a fltered clunk on the fill line but that's a bit of an over kill in my book.

I use a 3 line system as opposed to a two line with one as the vent and the feed line having a Tee in it for fuelling is a potential problem point which can introduce air into the system