The street avenger I have came with clear sight plugs that fit in those holes for tuning and screw in metal ones for permanent use.
This stuff should have come in the supplied hardware package with the fuel line, extra springs and such.
Those generic, one size fits all dual feed chrome fuel inlets often don't fit properly. Offshore manufacture I suppose. I would use the rubber/brass stuff that's supplied with the carb, or one of the braided steel setups from a real supplier if you want something prettier.