I have not played with my Tarno carb yet. The Queen Bee .074 responded well to an airbleed. It really did not idle at all before the mod. I saw the specs on one of the forums. I drilled the hole a bit smaller than the .062" recommended. I read somewhere that the Norvels needed the base of the carb housing opened up to a bit larger than the top opening like BMatthews mentioned. I have a new .06 that does not idle at all which I may try this on some day. I have since got a few more that work well, so it still sits in the disappointment drawer.