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  1. #1

    GP1200 65U Carb Pop-Off Pressure Question

    Hi,

    Straight to the point question: What is the stock pop-off pressure for a 65U non-pv carb? I tested mine and it came to Carb1=69-72psi, Carb2=68-70psi, Carb3=65-68psi.

    I've read somewhere that stock pressure for this engine's carb would be 65-70psi? Is that correct?

    Second question is that, would it be better if I rebuild the carb and tune it to 45-55 PSI pop-off? I'm not sure what the pop-off is for and so I'm still not thoroughly educated as to why tuning lowering (or increasing) pop-off pressure would be beneficial.

    Thanks.

    Ford
    Last edited by bford; 06-10-2015 at 07:48 PM.


  2. #2

    Join Date
    Apr 2010
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    Pop off can be a little bit of a dark art. In short at very small throttle opening and there not a huge airflow through the carb throat the correct pop off allows there to be in fuel in the carb.. I have a superjet and I notice more there than on my gpr.
    I run a bit lower cos when I pull the throttle I like to have the fuel in the carb and not have a starve. However after an extended run at low speed it starts to run a little rough.
    I assume you have looked at the Mikuni manual for the theory?

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