Grasping at a straw here along the lines of what Peanut was saying. Maybe you have overtightened the carb mount screws.
I have a set of 74/75 BS38'S that if I overtightened the carb mount clamps screws, the butterflies would bind and not fully return. Had to play around with them to get them just right.
Worth a try to back them off a bit before you throw in the towel.
I have a set of 74/75 BS38'S that if I overtightened the carb mount clamps screws, the butterflies would bind and not fully return. Had to play around with them to get them just right.
Worth a try to back them off a bit before you throw in the towel.