04 CRF 450R Altitude problems...
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    UteMachine
    Posts:167
    Joined:Fri Nov 10, 2006 9:09 pm
    04 CRF 450R Altitude problems...

    by UteMachine » Mon Jul 16, 2007 11:42 pm

    I am at wits end with this problem. Here are the vitals

    Bike- 04 CRF 450 R

    Conditions- Altitude from 4300ft Salt Lake City to the mountains at 7500ft, humidity around 37%, temps around 80-100 degrees, trail riding.

    Modifications- Thunder Alley full exhaust with quiet core insert.

    Current Jetting- 165, 42, and the clip is dead center.

    Running Issue- Whenever I ride in the mountains, give a burst of throttle, then pull the clutch in, it almost stalls or does stall. If I wait for about 5 seconds the idle comes back up. I've been told I am way too rich. I think it started around the time I put the exhaust on and I have never touched the jetting. Playing with the fuel screw does nothing to solve the issue.

    Problem variances- The issue seems to go away when I come down from the mountain to an altitude of around 4400ft. In fact, I usually have to crank the idle up while I am up the mountain, and by the time I am back down the idle is really high. The quiet core insert made the problem worse when I installed it.

    Thanks for your help!
    ImageImage

    "Kicking and a gouging in the mud, the blood, and the beer."
    -Johnny Cash
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    JAWS
    Posts:4449
    Joined:Fri Jun 16, 2006 6:59 am

    by JAWS » Tue Jul 17, 2007 6:34 am

    Your description does make it sound too rich. The main thing that changes with lower altitude is the presence of more oxygen. The JD kit has a needle and setup especially for altitude. You could give that a try. I suggest that you call him and inquire.
    Joe
    Image
    '05 CRF450X,McClain suspension, Cycra Probends, Pastrana FMX Pro Tapers,BRP Sub mount & Scotts stabilizer.See carb sticky for more
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    paul turner
    Posts:7578
    Joined:Thu Sep 22, 2005 9:03 pm

    by paul turner » Wed Jul 18, 2007 6:15 am

    We have the JD kit in Pat's 250r, and it runs flawless up to 9500'. I just drop the main one size for the KM trips only, then tweek the fuel screw at camp warmup. usually just in a little bit.

    paul
    If you ain't crashin', you ain't ridin' :-)
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  • User avatar
    UteMachine
    Posts:167
    Joined:Fri Nov 10, 2006 9:09 pm

    by UteMachine » Wed Jul 18, 2007 7:34 am

    Thanks for the input guys. I was trying to get away without doing the JD kit. I went to a 160 main and up one on the clip. If that doesn't work I will get the JD kit. Thanks again!
    ImageImage

    "Kicking and a gouging in the mud, the blood, and the beer."
    -Johnny Cash
  • User avatar
    Skoot22
    Posts:2380
    Joined:Sun Sep 03, 2006 9:51 pm

    by Skoot22 » Sat Jul 21, 2007 1:25 pm

    what i have found is usually a main jet is all you need to adjust at higher elevations. a 160 should help.
    Scott
    05 CRF450X
    Bakersfield, Ca
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