carb rebuild warnings ???

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  • north49

    #1

    carb rebuild warnings ???

    Hello CV carb gurus...... I'm getting ready to clean/rebuild my '80 GS1000G CV carbs. I've viewed the (excellent) GS Forum carb rebuild item as well as read service manual carb clean chapters.......so here's my question.
    In the service manual there are DIRE warnings about removing the air pilot screws. It says these screws are factory adjusted using specialized equipment etc etc.....and if you alter these settings then you may as well shoot yourself!! Do these warnings apply to CV carbs?? I'm planning on marking all adjustable screws and re-install them back to their original positions. This should at least get the bike running again so the dealer can balance and adjust them.
    So...once again.....do the air screw warnings apply to CV carbs?
    cheers and thanks for all comments
  • Nessism
    Forum LongTimer
    GSResource Superstar
    Past Site Supporter
    Super Site Supporter
    • Mar 2006
    • 35788
    • Torrance, CA

    #2
    The pilot screws are adjusted to meet emission regulations, not to optimize running. Standard procedure is to remove the caps over the screws and adjust them with the engine running to achieve the highest idle speed, which coincides with the best mixture setting.

    Edit: When I first rebuilt my '81 550 I set the pilot screws to 2 turns which is where they were from new. Short story is that the bike did not run right (possibly due to changes in gas over the years, and here in California) until I set the screws to 3 turns. The idle speed increased noticeably between 2 turns and 3 which is the key thing to look for when adjusting the screws. Start at 2 or so and turn slowly outward and stop when the highest idle is achieved - at some point, more turns will not cause a change.
    Last edited by Nessism; 09-30-2007, 09:39 AM.
    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

    Comment

    • Thomas Kenny

      #3
      Save yourself some possible grief. After you remove the caps, slowly turn the screws down to a soft stop and count the turns or portions thereof. This will give you your base line if you need to return to the factory setting.

      Comment

      • Guest

        #4
        You need to remove those to replace the o-rings

        Comment

        • txironhead

          #5
          Also, save yourself a lot of money and grief and forget taking it to the dealership. Most dealerships won't even touch a bike that old.

          Get yourself some carb synchronizers (also called manometers, carb synchs, carb sticks, vacuum gauges, vacuum synchronizers, etc.) for $40-60 and balance them yourself. It'll be cheaper than what they'll charge you at nearly any shop or dealership, and then you'll have a tool you can use on any carbureted bike you own now or later. You'll need one with 4mm adapters I think. A carb synch "wrench" will make things easier, those can be found for around $12. It's basically a long screwdriver with a socket around the head for adjusting the carbs while you're synchronizing them.

          Definitely replace the o-rings and the intake boot o-rings, it'll save a lot of grief down the road.

          Comment

          • Steve
            GS Whisperer
            • Jun 2005
            • 35925
            • southwest oHIo

            #6
            Originally posted by txironhead
            You'll need one with 4mm adapters I think.
            Actually, you need 5mm adapters, but what's one millimeter among friends? 8-[


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            Comment

            • txironhead

              #7
              So the GS1000 uses 5mm? I was told my GS750E uses 4mm, but I haven't reached that point yet so I'm not sure.

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