750 carbs correct ? Did you have that rack mechanism disassembled ? Most stock return springs have a rubber cover over them,maybe yours was removed ? Its looks kind of long also,is there a lot of tension on it and did you have to stretch it well to install. The slides should snap back with some authority. The other thing I notice is that your adjuster nuts at the top of the carbs are cranked down pretty far,I usually don't see that many exposed threads when set up correctly. Wish I had a rack here at the house to see if that wound spring is correct,see if you can find a good pic to compare.