Just the fuel screw or a rejet?

Since it has gotten colder, my '03 has started to get some backfire and stalling here and there, and I know it is just running lean, as is my dads WR250F. Just by richening it up by the pilot screw on the bottom of the carburator will that work or do I need to bust the carb open? I am not looking for every last ounce of performance I just want it to act normal. thx for the help

Yes I already did a search.

For temps below 60 - I would go up 1 on the main. From 165 to 168 or 168 to 170. Take drain plug off bottom of carb to get to it. Then readjust fuel screw.

Is the main and the fuel screw the only stuff I need to worry about????

generally, you might also need to adjust the clip on the needle (raising the needle to make it richer). There is no way to guess this stuff, you have to be willing to try it. The fuel screw would be the first thing to try, then the main.

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