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  1. #1

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    low speed booging

    Hi, quick question. I am having bad low speed bogging, top speed is ok if i can feather it up pass the 20%-50% range. the carbs is all fresh rebuild and tested. I am still in the process of tunning the carb. so my question is should i turn in or out he low speed needle? right now it is at 1 turn out per the spec.


  2. #2
    THE PLATE MAN JIM'S PERFORMANCE's Avatar
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    Quote Originally Posted by birdgod View Post
    Hi, quick question. I am having bad low speed bogging, top speed is ok if i can feather it up pass the 20%-50% range. the carbs is all fresh rebuild and tested. I am still in the process of tunning the carb. so my question is should i turn in or out he low speed needle? right now it is at 1 turn out per the spec.
    What kind of ski, if it's a power valve motor make sure the power valves are working properly.

  3. #3

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    Nope, yami SUV gp1200 motor.
    Ok, I pull he plug today and take a look, it is too rich, the plug has black and tick oil on it.
    I am going to turn in the slow speed needle by 1/8 at a time to see if it improve the bogging. If I remember right the I cannot have the low speed needle more then 7/8 turn in right?

  4. #4
    Moderator OsideBill's Avatar
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    what are your current jetting specs? and where are the adjuster screws currently set to?
    Turns out on the lows are 1 +/- 1/4 from the factory.
    Sometimes these have issues with the N&S opening early due to the motor vibration, and this floods the motor on low end. Are the carbs dribbling? it will have a slightly erratic idle if they are.
    One cure for this is to double up on the little check valve under the metering assembly that covers the jets. increasing pop-off helps too I do this by increasing the N&S to 1.5 and running Gold 115 gram springs. It gives me 3 PSI more but it helps.

  5. #5

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    Bill, my crab is all factory spec. The original n/s is 1.2 with high 65psi pop off. The idle is fine, once start, it just side nicely on idle not rpm increase or decrease. The problem is when I try to give it gas, it bog, I need to feather it and once it pass 60%. The ski run super fine.
    This problem also started after I break in the engine and change from 32:1 back to 50:1. Right now the low slow needle is 1 turn out. And the hi speed is 1,3/4,1.
    My plan right now is that to change new spark plug and adjust the low speed needle to 7/8 turn to lean it a little as it is too rich riht now. I will ride in the 20%-60% range to see if the problem is gone. If not then goes to 3/4 turn and try again...... What do you think?

  6. #6
    Moderator OsideBill's Avatar
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    is it dribbling?

  7. #7

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    Quote Originally Posted by OsideBill View Post
    is it dribbling?
    How do I check?

  8. #8
    Moderator OsideBill's Avatar
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    two ways to tell one I explained in my first post the other is to take the top of the spark arrrestor off and look into the throat while it is idling.

    Also 1.2 N&S and shiny silver 60 gram spring is the stock set-up, which should be 52 PSI pop-off

  9. #9

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    I got 2 suv the same time and they have the same 1.2 n/s. I check both before I rebuild them, all six carb have about same
    pop off at about 65psi. So I assum that it is stock. I can change the spring to gold and gt it to arround 50+, but I hope to do that last if the is any more solution. But the was if the psi is too high, shouldn't the engine run lean?

  10. #10
    Moderator OsideBill's Avatar
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    Since there is no published pop off for the 1.2 N&S I did quite a bit of tewsting and came up with results which I avereged. The 1.2 N&S with 60 gr spring is 52 PSI, anyways not to worry this is not the issue.
    like I asked twice before and for the last time now, are the carbs dribbling at idle?

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