What the heck is this carb bit and why don't I have one?

[mennobike]

So I was just browsing old posts, trying to get to know the bike better, and I stumbled across this:

I distinctly remember having the needle when I tore down my carbs (sort of have to) but I also distinctly remember not having that other piece. Is that something I should be concerned about?

Thanks!

[HPP8140]

Depends if you have the older 2 circuit or newer 3 circuit carbs. Not if you have the older carbs.

[mennobike]

Ahhh, yeah I have a '97. Suppose I should have thought of that sooner.

Thanks!