Carb adjustment Round 2: Fight!

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  • 79FiveFifty
    #1

    Carb adjustment Round 2: Fight!

    79 GS550 VM carbs

    Most of you know, I rebuilt my carbs and had an issue of leaning out.

    So, I replaced the float needles, and re-adjusted my floats to about 23.5 / 24mm I also set my pilot fuel screws 1 turn out from bottom. I set the air screws 2 turns out from bottom.

    Now last time I set the carbs, I believe I had the pilot fuels @ 1 and 1/4 and the airs at 1 and 1/2. I was running too lean.

    This time - I THINK I am running rich.. when I rev the bike it is somewhat hesitant, and then the rpm's hang up for a moment and proceed to drop very slowly back down to 1500 rpms. I can not adjust the idle any lower than that it won't drop. With the throttle on high rpms I get some popping in the exhaust.

    With that being said.. does the rpm hang up and slow drop to "idle" sound like a rich condition now? IF so what do I do about it.. what adjustments should I try on the screws now..

    Thanks for your patients.. hopefully I'll get it right sometime.
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    • almarconi
      #2
      With that being said.. does the rpm hang up and slow drop to "idle" sound like a rich condition now? IF so what do I do about it.. what adjustments should I try on the screws now..
      That is a sign that the bike is lean. I guess you still have not checked your fuel level yet?

      1500 rpm for a baseline idle is too high. You should be around 1000 rpm. Check to make sure your throttle cable has enough slack and that the butterflies can close completely.

      Did you check for air leaks at the manifolds? Spray some carb cleaner around them and see if the rpms increase.

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        • 79FiveFifty
          #3
          .. lean again? .. man. I definitely set the fuel level higher than it previously was via floats.

          I haven't checked the fuel level yet .. no vice / wasn't able to find any clear tube yet.

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            • Guest
              #4
              Originally posted by 79FiveFifty
              .. lean again? .. man. I definitely set the fuel level higher than it previously was via floats.

              I haven't checked the fuel level yet .. no vice / wasn't able to find any clear tube yet.
              Raising the float height lowers the fuel level in the bowls...

              The fuel level is measured while the bike is idling

              Clean the carbs & set everything to nominal OEM values.

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                • 79FiveFifty
                  #5
                  If it doesn't rain / snow tomorrow I will work on tuning the air screws on the side first, I have a feeling I have them too far open causing the bike to lean out. This sure is a delicate process.. it was enough tuning my truck to run right, now I have x4 carburetors.

                  This is why all of you are now bike mechanic I suppose.. just gotta keep working at it until I get it right.

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