Welcome to the forum Greg. It can be done with the carburetors in place if you have the tools to do so. You will need four o-rings and two gaskets. The bolts holding the cross-over tube ends to the heads are 8mm and I used a 1/4" drive socket set to get them out. Don't forget to clean all the old gasket material off the mating surfaces and the tubes. Be very careful of the tubes, they can be easily dented. Wet the new o-rings with anti-freeze before attempting to insert them into their receivers. You won't need any sealer for the gaskets if you cleaned the old material off completely. Put a little anti-seize grease on the threads and re-tighten them. The picture is from my 1100 and unfortunately the only one I could find of the area you need has the carburetors removed.