Throttle question.

Hey guys, I have a 1980 yamaha xs400 and went to put drag bars on it today. Inside the throttle side of the stock bars was a metal rod. Does anyone know what's up with that? I am going to need to reroute the throttle cable as well as the bike was racing as soon as I started it up, but I'm wondering what that thing in the grip is and if I need it. Does anyone know what I'm talking about? Do I?

it's a free floating weight, guys. It's cool, I figured it out.