How many of those rubber carb sync port covers are on the bike?

I found a random rubber carb sync port cover down in one of the crannies near the twinkie. My manifolds 1, 3, and 4 have the port covers in place and manifold 2 has the vacuum line. I'm not sure how in the world this random one ended up there and I don't see how I could have missed it after the detailed inspection and cleaning I did during the refurb a couple years ago.

Is this same port cover used somewhere else on the bike that I'm not aware of?

Not that I am aware of.

I have seen some brake bleeding nipples that have a rubber cap. Though I don't know how it would have migrated from a caliper to the engine. Senior moment? You lost one once upon a time and didn't find it?

Senior moment? You lost one once upon a time and didn't find it?

I wish! I've had the same 3 caps since I purchased it from the PO in 2001. Never purchased or used any extras. I'm guessing that the PO lost one in the black hole and it recently came loose from the black hole & fell down by the twinkie between #1 and #2 . Just discovered it after a 1,300-mile cross country.