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03 XR 250 Question

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Just bought my 03 xr250 about a month ago. It is clean and runs good. When I took it apart I found that the previous owner took off the snorkel to let it breathe better. To my knowledge nothing else has been done. I have since put some uni filter foam over the hole to keep out some debris. Should I go to a uni filter instead of stock air filter? Do I need to re-jet the bike. Does the pilot screw need to be adjusted? Living in CA it looks like the jets are smaller than other parts of the country. I don't really want to buy a new exhaust or mod out the original. I have already read about the mods. What will happen if just the air cleaner is opened up? Thanks for any input.

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normally taking out the snorkel requires increasing to the next jet size.

I would go to a Uni- the stock filters have a restrictive screen and they tend to fall apart where the base is glued to the foam. With stock exhaust a Uni and no snorkel 1 jet size is probably ok. jetting is trial and error.

I would also back out the mixture screw 1/4 turn.

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Kiehin jet sizes usually end in 0,2,5 or 8. So next size up main would be a 125, next size up pilot would be a 48. Always best to make sure you know what you have in there now and how many turns out the fuel screw is before you change anything. That way you have a baseline and can return to those setting and jets if it doesnt run well. :thumbsup:

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I will double check the sizes of the jets (are they written on the jet?). Any ideas on causes of backfire on deceleration. Will re-jetting fix this? I know, to some these are probably rookie questions that have been asked before, but I can't find them (at least not exactly).

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I will double check the sizes of the jets (are they written on the jet?). Any ideas on causes of backfire on deceleration. Will re-jetting fix this? I know, to some these are probably rookie questions that have been asked before, but I can't find them (at least not exactly).

No problem man. I never had much luck with the search function here either.

Ya the #'s are on the jets. Decel pop is usually because your a little lean. Try turning the fuel screw out 1/4 turn at a time and see if it goes away. 2 1/2 to 3 turns out max though, past that just get a richer pilot (slow) jet in there.

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Okay, just put the new jets in today. Went from 132 main/45 pilot to a 135 main/48 pilot. Have lost the backfire, bike fires right up, front end comes up much easier. Still need to put on uni filter. Will post back with results. Thanks for the input. Fairly cheap fix. The 48 pilot was 3 times the price of a regular jet for some reason. Maybe someone knows that's the one that works (supply and demand).

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