An intake tap is used on a few engines and the purpose is the same as it is in automobiles as case vent recirculation system. Cleaner more complete burning of the fuel with an added bonus of the lost oil recovery for at least one more cycle. It is not a huge issue and does not have to be used however if not, it should be capped with a vacumn cap. If left open it can cause eratic leaning of the mixture. Never run an intake tap to the tank vent. This is a vacumn line not a prssure line such as we have from the muffler and will hamper fuel delivery from the tank.

John