Altitude Jet adjusting ?

Discussion in 'Engine, Fuel and Exhaust' started by rgp332, Aug 14, 2010.

  1. rgp332

    rgp332 New Member

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    I live at 800 ft altitude and planning on traveling to Colorado riding around 6000 altitude. What does anyone suggest?? Bike is 99 Evo 1340cc with Keihin CV carb. Any suggestions would be greatly appreciated
     
  2. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

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    Are you gonna be spending a bunch of time there, or just a trip there and then back home? If the latter, I would just reset the idle/air mixture screw when you get there, and reset it when you get back.

    If, however, you are moving to Colorado on a permanent basis, you probably will want to rejet. May only need to fiddle with the low speed jet.

    Let us know what the situation is, and what you have in the carb now.

    TQ
     
  3. kemo

    kemo R.I.P

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    The C/V should compensate for this trip, that is the beauty of this carb. As TQ suggests you might just need to fiddle with the mixture screw.
    Kemo
     
  4. NEWHD74FAN

    NEWHD74FAN Experienced Member Retired Moderators

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    Actually with the lean mixtures what they are nearer sea level, going to higher altitude makes bikes run BETTER...albiet the air is not as dense enrichening the mixture. From the seat of pants perspective, maybe a "trifle softer" but not really much difference as your CV carburetor (slight delay of the diaphram response) makes throttle response to actually feel more crisp. As TQ says, longer living at high altitude means you can optimize there for best performance.
     
  5. rgp332

    rgp332 New Member

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    alright heres what I figured out,I had a 48 slow jet and 185 main in it. I changed it to 45 and 175. Ran good,I rode it up to almost 12,000 and it ran fine. After a little playing with it I can change the jets in about a half hour.
     
  6. BUBBIE

    BUBBIE Well-Known Member

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    Food for thought: I find that the Phillips screws on the carb bowl are better replaced with allen heads and much easier to in-out on the bike... I never remove carb to change out...

    The allen head replacements, IF memory serves me are 5/8 of an inch... I hate when i strip the phillips head and have to pull carb to get it out!:small3d023:

    signed....BUBBIE
     
  7. 2kstdbagger

    2kstdbagger New Member

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    I just moved to NM, about 5000' elevation. Bike was sluggish. I was told to rejet the carb. HD put 165 main jet and 40 pilotjet. Carb was "burping" every 10 seconds. I took it back and they said i needed new intake gaskets, which they installed. Carb still burps when i throttle back and in 3rd @ about 2700 rpm. Maybe i should just go back to the jets i had before i got here. At least it wasn't burping. ANY ideas???
     
  8. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

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    Assume you have the Keihin CV40, right?

    If so, WOW. Those are pretty small jets. What did you have in there before?

    Here is some basic info:

    *Twin Cam CV Carb Rejet Suggestions - Harley Davidson Community

    Here is some info on trouble shooting:

    CV Carburetor Jet Adjustment/Trouble Shooting - Harley Davidson Community

    TQ
     
  9. fin_676

    fin_676 Experienced Member Staff Member Moderator Contributor

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    If you do have the stock cv carb then it should compensate for the lower air density automatically and jets should not need replacing
    from the size of jets you gave i would think they are very small at least the slow jet would be much better at a 45

    Brian
     
  10. 2kstdbagger

    2kstdbagger New Member

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    Thanks TQ and Fin. I had a 46 and 185 when i got here. Stock carb. I seemed to have lost a little power but no burping. I went on the advice of someone @ HD shop. Just going to go back to the jets i had and use the mixture screw for fine tunin it. Thanks again for the links and the advice!

    -------------------------------------------------------------------------

    Also, someone @ service told me that they rode my bike "around the block" to test the jets. wow. Going to find an independent service center, I've had it with this dealer. Their final suggestion was to dynotune it for $150 minimum. I'll follow you're advice. Thanks again.
     
    Last edited by a moderator: Sep 26, 2010