05 crf 250 with White bros. Carbon Pro

Kit came with 150 main and leaner pilot jet. Stock is a 172 main. 150 seems awfull lean! Scary lean! I left jetting stock and rode it in 60 degree temps here in Minnesota (sea level) Seems like it revs but goes nowhere. Back fires on deceleration. With stock pipe it backfired even worse though. About 8 hrs on bike. Temps are in the 50-60's. I am an A rider and like to rev the bike out.

Just took out airfilter screen and put new White Bros. filter in. Going to Millville this weekend and was wondering if anyone had any jetting specs for this bike pipe combo? JD????

Oh yeah just got zip-ty fuel screw and installed last night. Set it to 1.5 turns out.

Rejetting not a problem, have lots of jets, experience, just need some pointers or base line that has been working.

Thanks Much! :cry:


The JDJetting kit for the CRF250R recommends about a #175MJ in your case. Only the CRF250X would use main jets smaller, due to a more enclosed airbox.

If you want to focus more on top-end, try a #168-170 main jet.


JD what about pilot and needle clip. I rode it this weekend at Millville and the thing ran like a 2 stroke? No power band just blaaaahhhhhh! put bigger and bigger main in until i got to 182mj. Not much better. Same blahhh. Fuel screw was 3 turns out.

thank you! :cry:

Use a smaller main jet. If the top-end is running weak and just making noise, try a #168 main jet.

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