Can anyone help with a jetting question?

So i just picked up a 2004 crf250R a week ago and trying to get it set up. Here is the info:


Sea Level (Bay Area Cali)

Stock Carb

FMF 4.1 Slip on (Stock headers)

Just ordered a moose racing jet kit since thats all my guy had in stock atm


Let me know any other info is needed.


Appreciate the help! I couldn't find much except on the fmf website which said it needed a 400 something main jet? that didnt seem right.

Ride your bike. Identify issues. Then resolve those. Do not fix what is not broken.


If you must have a jet kit, order a James Dean one. The FMF is really a repackaged DynoJet one and the jets are proprietary to DynoJet and the numbers do not match any jets other than theirs. James Dean uses OEM (Keihin) jets

agreed.  you wasted your money on that jet kit.


the 250fs are pretty well jetted from the factory except the AP circuit. 


up the pilot to a 45, adjust the needle to the 4th clip and adjust the fuel screw.  Then if you have a AP cover with adjustable leak jet (factory R&D, Boysen 3 or the factory r&D bowl), you can dial in the bike perfectly externally with a screw driver.  helps to have an extended fuel screw also. 

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