Air box modification on CRF 250X
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    rstappenbeck
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    Air box modification on CRF 250X

    by rstappenbeck » Thu Jan 04, 2007 4:00 pm

    Hello Everyone,

    My question is, what is the process of modifing the air box on a CRF 250X? I have seen how to do it on the 450X but the 250X is different.
  • Asmith
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    by Asmith » Thu Jan 04, 2007 4:11 pm

    What differences are causing you grief?
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    rstappenbeck
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    by rstappenbeck » Thu Jan 04, 2007 4:27 pm

    Hey AS,

    I pulled both side number plate's off, I have my bike's silencer off, I pulled the seat and battery to get to the top of the air box and snorkel and removed the rubber top of the box under the black metal bar...

    But my confusion is...

    On the air box access side(left side) of the bike there is no black false cut out, like the 450's have those on both sides(I think). The 250X only has one on the exhaust side. But mine does have a false cut out on the silencer side(right side) of the bike, but when I pulled it there is some wires and things behind it, the air box does not back up to that side number plate, if you were to cut out the black slot there would be 3/4 of an inch between the number plate and the box. But the actual air box cover that you can open does not have a false cut out, but it looks as if that is the only place that I would be able to cut a vent into to actually let the air box breath, please help!!!
  • Asmith
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    by Asmith » Thu Jan 04, 2007 4:47 pm

    I only cut the top off my airbox. I didn't cut the sides at all. I think you get the benefit from that alone.

    Here is the actual Honda document explaining the CCC mods.

    Image
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    rstappenbeck
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    by rstappenbeck » Thu Jan 04, 2007 4:57 pm

    So you think that with me just peeling off the rubber top of the snorkel that should be fine?

    -Randall
  • Asmith
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    by Asmith » Thu Jan 04, 2007 5:01 pm

    rstappenbeck wrote:So you think that with me just peeling off the rubber top of the snorkel that should be fine?

    -Randall


    No, you still have to cut the remaining plastic off the top like the picture indicates. In the "After" picture it shows "cut along this line".
    Use a utility knife and heat up the blade with a propane torch or even a lighter. Makes easy work of it.
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    rstappenbeck
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    by rstappenbeck » Thu Jan 04, 2007 5:02 pm

    Thanks for the Sheet!!

    On number 8 it is talking about a "pink wire" what does that do if you switch it?

    Randall
  • Asmith
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    by Asmith » Thu Jan 04, 2007 5:12 pm

    rstappenbeck wrote:Thanks for the Sheet!!

    On number 8 it is talking about a "pink wire" what does that do if you switch it?

    Randall


    Changes the ignition curve to that of the R. Also increases the rev limiter by 500 rpms.

    I don't think you will notice any increase in power without changing to the R cam.
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    rstappenbeck
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    by rstappenbeck » Thu Jan 04, 2007 5:34 pm

    So should I probably leave that alone??
  • Asmith
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    by Asmith » Thu Jan 04, 2007 6:03 pm

    rstappenbeck wrote:So should I probably leave that alone??


    Either way...doesn't make much difference.
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    rstappenbeck
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    by rstappenbeck » Fri Jan 05, 2007 2:22 pm

    Okay,

    I put the E2 on and cut out the top of the air box and went for a run up the street and when I would twist it, it would just fall on it's face. Please HELP!!!

    What can I do to fix this???

    Thanks Randall
  • Asmith
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    by Asmith » Fri Jan 05, 2007 2:24 pm

    What jetting changes have you done so far??
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    rstappenbeck
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    by rstappenbeck » Fri Jan 05, 2007 6:16 pm

    None so far I am waiting for the JD kit to come. But I am really frustated the way it is now so is there anything else or some needles I can buy from Honda to fix it tomorrow?

    thanks Randall
  • Asmith
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    by Asmith » Fri Jan 05, 2007 6:25 pm

    Sure,

    we can get close. Move your needle to the 4th or 5th clip. (probably on the 2nd clip now) and change the main to a 158.

    The main jets can be obtained from Honda for about $ 9.00. Just buy one as you will be getting them in your JD kit.

    The Honda part# 99101-357-1580 for the 158.

    Open your fuel screw up to 2 turns.

    Should run pretty good.
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    rstappenbeck
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    by rstappenbeck » Fri Jan 05, 2007 7:00 pm

    Thank You so much!!

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