Many moons ago I designed and posted a mod on the old site a really good improvement that could be made on the cv carbs. Basically the plastic washer under the needle wears significantly through rotation and if they do no rotate they groove severely.  Also the way slide is designed with a step so the plastic washers causes the needle to sit at an angle causing even more wear on the Suzuki emulsion tube top area causing ovality and richness, which is compounded even more if using rubbis