I'm pretty sure this very part is the reason I got my 2013 dirt cheap. No matter what I did on this part, it would siphon gas around it's outside diameter into the venturi and mess up the mixture (especially at WOT) and I suspect it was a defect in the main carb body not the nozzle. I bought a new carb and my TW ran like a top. Had to pull off the airbox to see it happening in action even at idle.