08 GV250 – need help identifying carb part (please?)

I bought a carb rebuild kit and though I am experienced, as far as automotive mechanics go- this was, admittedly my first time doing so on a bike.

I accidentally turned this small nut too tight and broke the head off.  I can’t seem to find anywhere in the service manual(s) where it identifies this part/number.

Any suggestions on where to get another part, so i can finally put my project back together?

Thanks in advance!