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  1. #1
    stubburnjdh's Avatar
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    pop off pressure?

    I Just was wondering everyones opinion on pop off pressures. What is the range everyone shoots for? I know you want to get the carbs as close as possible to each other. Stay within 1-2 psi on each carb? I guess it also depends on the setup too.


  2. #2
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Follow the manual for pop off. Unless you've done modification, then you're on your own.

  3. #3
    stubburnjdh's Avatar
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    I was just reading in another thread about a 1100 zxi that the guy was told by a local Kawasaki shop who used to race them said to drop the pop off to 12-13 psi for quicker throttle response. Is this accurate or just for race applications?

  4. #4
    johnsonmtz's Avatar
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    Quote Originally Posted by stubburnjdh View Post
    I was just reading in another thread about a 1100 zxi that the guy was told by a local Kawasaki shop who used to race them said to drop the pop off to 12-13 psi for quicker throttle response. Is this accurate or just for race applications?
    It's entirely dependent on the engine's fuel demand. My SLT 780 calls for 22-24 PSI. I haven't experimented with pop-off, but I would venture to guess if I had 12PSI the ski would load up terribly under low speed conditions and probably foul plugs. Crisp throttle response is all about having just enough fuel at idle/low speed for the engine to run well and have ample fuel/air charge in the case when you nail the throttle. If you get too much fuel the mixture is rich, you get poor spark, and poor performance. Remember, lean is fast. The trick to have just enough fuel to meet demand for maximum power, keep combustion temps in the right range, and avoid melting pistons.

    If your ski is stock I'd suggest just going with the OEM spec pop-off pressure. You can dabble a bit with low end response by adjusting the low speed needles. If you haven't already, download the Mikuni SBN Manual and read through it. That will give you the complete layout on how these carbs operate and help understand the effects of altering settings.

    KJ

  5. #5
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    Another thing to check is to make sure the arms that move the inlet needle aren't bent. If it is bent down too much it will run lean, effectively changing your popoff.

    Check to make sure you have the correct needle and seat as well as the correct spring. Have you disassembled the carbs to verify you have all of the correct jets installed?

  6. #6
    casey67's Avatar
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    Not sure what carbs that racing Kawi was using.
    But the accell pump on a Keihin in a way acts like a lower pop-off.
    IE: When you jump on the throttle, you get extra fuel for the sudden increase in air.

  7. #7
    urugol's Avatar
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    Just lowering your pop off probably won't do anything for you in stock form, it will probably be counter productive. These adjustments are a bit of a science as well as trial and error, so jetting, fuel delivery, compression, pipes, reeds all need to come into the equation. In stock form you should be aiming for the factory spec at all times. I just rebuilt my carbs and have them at the exact same pressure on each carb.

  8. #8
    stubburnjdh's Avatar
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    I got my pop off to 23-24 on each carb on my sl900. That is with the springs that were in it. The carbs are stock with stock jets. I also own a 1100 zxi that has keihin carbs and am surprised to see that the polaris 38's are larger bore on the choke side and funnel down. The 1100 zxi 40's are smaller on the choke bore with less of a funnel.

  9. #9
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    Make sure all of your jets are in the right places as well. I just opened up my 900 carbs after seeing this thread and found that the mag and cen high speed jets were reversed........not real good. I also need to figure which one is the low and which one is the mid so I know those are in the right places.

  10. #10
    stubburnjdh's Avatar
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    My 900 actually runs really good. It gives the 1100zxi a run for the money. It runs 58 on the gps all day long. Was just getting everyones opinions. Always love good info.

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