Still would be nice to know how much of a teardown was done. Were the crabs split? Only the bowls, jets and floats removed. This info could help in narrowing down the area where this part could come from.
Coreless, I'm pretty sure the cylindrical part you have left over from your carb project is actually a tool or universal part from the AIS removal kit. My Roadie kit had one and pics of the kit shows what appears to be what you have.
Great bike that V-star 1100 I had one for a couple of years, good power and handling, fantastic brakes. I was forced to trade it in I could not ride it for more than half an hour at stretch due to the riding position which was killing my back. That being said it was not the bikes fault it just did not fit me.