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  1. #1

    Gp1200r jetting help

    I've gone through the jetting specs listed by Fercho and I did not see specs for my application and looking for some help.

    Current jetting in stock carbs, no internal mods
    Pilots 110 2 turns out
    Mains 125 1 3/4 turns out
    Srping 90g
    N/S 1.5

    Mods:
    stock 1200r motor
    VF3's
    D-Plate
    Flame arrestors
    Advent ignition YAM 84
    Free Flow exhaust
    41cc domes (145 PSI)

    Thanks for any help.

    Wagz
    Last edited by WAGZ102; 07-14-2014 at 03:23 PM.


  2. #2

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    I think you would be right on if you used the specs in O'Side Bills thread in How to and FAQ, 110 pilot/1 turn out, 120 Mains/1 turn out, and 1.5 N/S with about 42 psi pop off. You are way too rich for the limited mods you have.

  3. #3
    Made a mistake, my N/S is 1.5, not 2.5 which i originally posted. I will turn the lows back in to 1 turn out and see what happens.
    Can anyone explain how to tell the difference between a lean or rich reaction on the low end?

  4. #4

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    Go to www.groupk.com, and look in the tech section, a whole lot of info about carbs and tunning.

  5. #5
    My only concern was the VF3's and slight bump in the compression from the heads would require more fuel on both the low & high end.

    I will check out the thread.

  6. #6
    Here is the plugs after a chop test. I ran wide open for 10 seconds, pull the kill switch while leaving the throttle open.

    My first run was showing very light color. (1 3/4 turns out) RPM's 7220

    My 2nd run (which is pictured below) shows a very light tan and still seems lean (IMO) RPM's 7150

    Any thoughts/opinions always appreciated.

    This is the rear cylinder.(PTO)
    Click image for larger version. 

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    This is the middle cylinder
    Click image for larger version. 

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    This is the front cylinder (MAG)
    Click image for larger version. 

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  7. #7

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    That carb tuning Group K thing I mentioned talked about monitoring rpm and watching for changes while at full throttle. Highly recommended reading if you want to know which way to go, far better than reading plugs honestly. The part you read on the plug is way down inside, not the tip.

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