I see lots of carbs 'rebuilt' but the lead/aluminum plug were never removed. If new ones come in the kit then they should be replaced as they can leak... plus its the only way to clean the passages thoroughly.
Lead shot or fishing weights also work well as plugs.. as do rivets.
Not sure about the carb you used, but if you don't use the proper carb gasket it blocks a vacuum passage to the governor (you probably don't have a governor, but some carbs do have a passage on the bottom).
