[nussford]

Hey guys. Newbie to the forum. Gotta question about jetting. Bought my 2012 250x new. Thinking about rejecting it. Got factory exhaust no spark arrester. Thats all thats done to it. Was thinking of doing the air box mod. So with that said what recommended jetting do you suggest with opened factory exhaust and opened air box. I'm also at about 800 ft elevation.

[crfsonly]

Welcome to CRF's Only. I recommend the JD Jetting kit we offer. We've had great results with it.

http://www.crfsonly.com/catalog/product ... ts_id/1096

Ken

[Deanzo]

Hey nussford,

I have a 2012 250X as well, and just sorted my jetting a few months back, a thread about it here http://www.crfsonly.com/forum/viewtopic.php?t=40089


If you do as I did, and order the Jetting kit listed above by Ken, then it comes with a table telling you what to use/install/run.

To be 100%, I e-mailed JD Jetting via their web site and listed everything, in their replys they were super helpful and really fast with them. Even though I ordered my kit here and not via their web site.

IMO if you are re-jetting, do the top of the air box (use a super heated blade, super fast and zero mess) take out the back fire screen and change to a super flow kit or the likes.
I hated the stock exhaust with no spark arrester, so I change that out as well, went with a FMF 4.1 with the q-core spark arrester installed.
For me, it fixed the issues I was unhappy with.

As I have just done all this on the same bike, if I can be of help, let me know.

[nussford]

What size and brand does the JD jetting kit use?

[Deanzo]

Do you mean what Needle do they use ?

If so, their own.
Kit will come with two, one with a Blue dot on the top, the other with a Red dot.

The Blue is for cold temps, the Red for warm.

Pilot Jet in the Kit is the same as in your bike a 42

Main Jets, off the top of my head (need to check) a 155, 160, 165 maybe one other (150 think ?).

And a table to work out what you should use for your altitude and temps, as well as what mods you have done. ie: If only the spark arrester diffuser has been taken out or something like my FMF installed, the main jet is a 155, if you have also opened up the air box, then you use the 160, if you also bin the back fire screen you run the 165

For where I live, in the winter, I get over night frosts, then in the summer, can be very warm.
This kit lets me run the "Blue" needle with the clip in the 2nd spot when it's very cold, then in the summer, the "Red" needle with the clip in the 5th spot.
The kit for me anyhow, took away all the guesswork, and has back up if you want to know something.
Which for me, was the big selling point.
Their table was bang on for me and my setup YMMV