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    VM air mixture screws

    After installing a Stage 3 Dynojet kit in my VM26s, I roughed in the mixture with the fuel screws on the bottom of the carbs, but the air mixture screws seem to have no effect. I've tried to use them to max the idle RPMs, but none of them seem to affect the RPMs. Anybody have any insight or suggestions? I also get either bogging or starving out above 3500 RPM, but I moved the needle clips from second groove from the bottom to the third groove, as it seemed really rich before I did this. I found this out while trying to run at 5k RPM to do a stator test (charging system just went down; a short blew the R/R and the stator).
    1979 GS 1000

    #2
    Bump! Any input, anybody? I need to get this motor to run halfway decently so I can run it a 5k to check out the stator again before I replace it. The accepted method to tweak the air screws is for max RPM, but I get no change with adjustment.
    1979 GS 1000

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      #3
      Just adjust the screws for best running and don't worry about the highest idle business.
      Ed

      To measure is to know.

      Mikuni O-ring Kits For Sale...https://www.thegsresources.com/_foru...ts#post1703182

      Top Newbie Mistakes thread...http://www.thegsresources.com/_forum...d.php?t=171846

      Carb rebuild tutorial...https://gsarchive.bwringer.com/mtsac...d_Tutorial.pdf

      KZ750E Rebuild Thread...http://www.thegsresources.com/_forum...0-Resurrection

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        #4
        I'll try that tomorrow. Thanks very much for the input!
        1979 GS 1000

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          #5
          Originally posted by Nessism View Post
          Just adjust the screws for best running and don't worry about the highest idle business.
          I'm with you Ed. Some people get paranoid about highest idle procedure. Adjust for smoothest running at idle. Also check spark plugs after it has idled for a while

          BTW what is the fuel screw set at.

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            #6
            After trial and error, they're set at about 1 1/4 turns out from lightly bottomed out, and she starts and idles pretty well, but the idle hunts like it is slightly lean. Before setting the screws to this point, she was running really rich. I ballparked the air mixture screws at 1 turn out, then tweaked the fuel screws 1/8 turn at a time until she started with the enrichment circuits on, then no choke after a minute and decent idle. BTW, I found out the hard way that if the circlip on top of ONE of the enrichment needles is missing, my bike will not start. It started fine before, but I must have lost a circlip when I took the carbs off to lower the needle in the main jet when she was bogging out above 4k, then she wouldn't start after that. I happened to notice the clip was missing, and the enrichment needle on carb #1 wasn't raising and lowering like the other three, only the bushing was moving with the other three. Replaced it, started instantly.
            1979 GS 1000

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