Jetting my 04 250x with mods.

I am sure it has been covered but i cant seem to find it on my search. I have a 2004 crf250x. Right now the head is being rebuilt and I am putting it back togeather with some mods.

Current set up is full R exhaust, cut air box, stock everything else...Main jet is 155 pilot is 42 and leak is 55...needle is in stock position.

New set up will be addition of 2006 R cam, 2008 R piston...13.1 i believe is the compression ratio.

I figured I would have to rejet for the new cam and figured that this more or less turns this motor into a 250R motor.....I know there are trans ratio differnces and newer 250rs have a larger bore carburator. I have been told that the 250 R and X head in 2004 were identicle...Mine is a California X so it has the smog pump port. I will also be disconnecting the Pink wire for the more aggressive ignition curve and higher rev limiter....I am running pump 91 octane fuel.

I live at around 500 to 1000 foot altitude. I have been told that a 165 main should be good. I was wondering why the R forum has there mains in the 170 to 175 range?.....Also what clip should I move the needle too?

Thanks ahead of time.


runs well with current jetting?

165 max main jet.

Get the JD jet kit and do put in the 165. Also put on the "O" rings for the accelerator pump. The kit has great instructions with lots of pictures. The kit has two needles. One is blue and has the clip in the fourth groove from the top. I think. It was perfect for my bike. I don't have the R cam.

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