I have always been suspicious of those rubber caps (2) I installed on my carb ("carby" to OZ and U.K. TT'ers:) ). At one point, I noted one of the caps dry rotted, and the other was sliced (I opted to lockwire mine in place). At one point in it's life, my bike felt like it was running WICKED lean, especially on the top end. After FINALLY getting all the parts I needed and ACTUALLY having time to work on my bike (since my last ride early June at Bill's ) I sat looking at my carb last night, again ready to install new rubber caps. The fittings are brass on the carb and I thought to myself, "Now what on God's green Earth goes better w/ brass than some flux, silver soldier and a blowtorch...?"Pretty much nothing. I found some thin cardboard, fluxed and heated the brass nipple and filled the (airbox end) air horn fitting w/ soldier. The thin cardboard I used to plug the inside of the airhorn to prevent the soldier from running out. (I held it flush w/ the inside of the air horn.) The other nipple, that connects to the pilot air matrix, well I left that alone FOR NOW. I am too far w/ my bike, and did not want to take off the carb again. I filled this nipple with liquid metal, and reinstalled a new rubber cap. Engine vacuum SHOULD NOT draw the metal into the carb (after hardening of course) as long as the rubber cap holds. I actually did think to grind the extended nipple and then fill the rest in w/ soldier. This would give a great streamlined look (should decrease lap times...you know wind resistance and all! ) It was quick, easy, painless and best of all, no rotting rubber can give me a vacuum leak!