I found this old thread while working on my carb and finding the outer part of the plugs, loose in the bowl ( they look like tiny- tiny black plastic spools ...about the size of a bb from a bb gun)....And not knowing what they were , I continued the cleaning...and found the pick-up tubes blocked (not knowing there were plugs) ....Note...2 brass tubes with a few tiny holes through the sidewalls ...extending from the carb body into recessed holes in the bowl..
Note: these are supposed to be blocked off at the end.
Not knowing this, I soaked and ultrasonically cleaned and poked the blockage in to the tubes like the originator of this thread knew better than to do. Throwing caution to the wind...I did not see this debris come out ( the passage is not straight) and thought it must have broken down into particules....but now I am doubtful of that.
So
I am a bit concerned, but, after installing makeshift replacement plugs, the engine runs great. The possible internal blockage didn't cause any problems (YET...at least in my 5 minute run test)....The engine started right up and ran great.
I am greatful for this thread because it was all I could find to explain those loose items in the bowl were and it let me know to cap the tubes. Good luck figuring that out from the carb exploded views at the part sites
BTW, these plugs are Part Number:16168-Z0A-004 on a Mikuni carb off a GXV530 HONDA engine.
Search the part number to get an image of the plugs.