My XR has a lean spot just off idle. In cold weather, it's worse. Giving it more fuel screw or pilot jet is not the answer, any richer and it loads up or puffs out black smoke. I know, the standard procedure is to shim the needle, and I have already done that. But consider this: the shimming only affects fuel mixture when the throttle is opened far enough for the tapered section to regulate the fuel flow. At low throttle openings, the DIAMETER of the needle is what matters. Shimming the needle too much just makes a rich spot at mid throttle and doesn't solve the lean hesitation just off idle. Does anyone offer a smaller diameter needle? Has anyone tried this? A larger needle jet may also work; not sure if the needle jet is even replaceable in this carb though. thanks!