Well, I'm running the T-15, and i did adjust the hsn first (since the hsn controls overall fuel flow, and the lsn just the low-speed fuel flow). But, as I said, when you unscrew the bronze hsn casing from the carb body, and pull the fuel inlet off the hsn casing, that was all full of grit and junk. there were no O-rings in there, just flimsy paper gaskets.