My '95 GSPD has always missed slightly under very low load conditions. I've been fighting it for years. New Metering Needles, New Needle jets, new Diaphragms, etc. etc.. By contrast, my '88 RS has always run wonderfully. Last week I swapped carbs between the two bikes, and, as expected, now the GSPD runs sweetly and the RS.. not so much. The book calls for all the same parts (jets, needles, etc..) but I tore down both sets to compare. Needles in the same grooves, same jets (135, 2.66, 45)... everything I could find was identical. WTF?? Then I noticed on one of the GSPD carbs that the little domed piece in the center of the carb top is LOOSE. It's loose enough to pass some significant air in a highly scientific 'suck' test. I've never heard of this before. Is it common? I'm thinking of floating some epoxy into that junction. Anybody have experience with this?