04 250X new mods need jetting help

[Son of Thunder]

Working on my wifes bike. Putting in a 13.5:1 piston, 04 250 R cam, new valves, intake and exhaust ports cleaned up and polished. I already have opened up the air box, smog block off, boysen quick shot, 250R header pipe W Jardene exhaust, 152 main, 45 pilot, stock needle lowered the clip 2 positions,( going to replace needle with 16203-men-671) Zip Ty fuel screw 2 3/4 turns out, pink wire cut. I live in So Cal elevation 3000. I am requesting help with the jetting as I believe I will need at least a bigger main. I talked to a friend who said the stock main jet in an 06 250R is a 170 so I was considering changing it to that. My wife is a very good rider and we like to go to the local tracks.

Thanks for your time.

[Jaketinaboxer]

im running a 165 onthe factory head and piston opened up airbox and a pipe.

[highmarker]

Most year R's use a 40mm carb vs. 37mm on the X. You can't compare main sizing directly. The X generally will need a smaller main than an r built with the same parts.

You also cannot compare directly with JD kit main sizing because he uses fatter needles.

IMHO, many X's are over jetted because of this.

[Codeman00]

im running a 165 onthe factory head and piston opened up airbox and a pipe.

Jake, aren't you running the JD Jetting kit? If you are, then his jets and your jet numbers are not comparable.

[Son of Thunder]

Thanks for all the useful info. I have a 160 main and a 168 main. Should I use one of these or get a different one? I just wish it was as easy to change the mains as it was on the ol 2 strokes!

[Codeman00]

Are you running the JD Jetting kit or not?

[Son of Thunder]

No not using the JD kit. I have a 250x closed course competition only use sheet I got directly from Honda. Going by the mods it says to use. It does actually recomend a 152 main. I put the 152 in a long time ago when she was running the stock cam. The mods do call for the R cam. Since I have cleaned up the ports I thought I might want to go up on the main.

[Codeman00]

I would estimate that you would go up 3 to 5 on the main...it just depends on how good the polish job is. 160 will probably be a bit too high.

[Son of Thunder]

Thanks. The polish job is really nice. All high spots taken out and polished very smooth. What main are you running?

[Codeman00]

I'm running a 165 with the JD kit. I have a friend that is getting a port & polished 250r head for his 250X. Agent Smith from AS racing said that he should try a 168 or 170 main. That's why I advised you to go up 2-5 on your main.

[Son of Thunder]

Thanks for your reply. I will try the 160 since I already have that Jet. Just got done putting the top end together so will rejet the carb and go riding!

[Jaketinaboxer]

Jake, aren't you running the JD Jetting kit? If you are, then his jets and your jet numbers are not comparable.

sorry it took me so long to see this, yes i'm running a jd kit, that's what it says in the paperwork, 165 main if your running an opened up exhaust. I thought it sounded a little rich, but the bike screams so i havn't messed with it.