160 is likely too big, most who have had them in a stock bore engine have found them to be too rich, myself included. What do you have in there for a pilot? Shim will add a little more fuel so then making the 160 seem even larger. I would first try a main around 150 to 155 depending on your elevation and couple that with a 45 pilot. Wouldn't shim the needle yet but maybe shim if the smaller main doesn't help.

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