Varify jet sizes for GS1000G

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  • Matchless
    • Feb 2026

    #1

    Varify jet sizes for GS1000G

    Hi, I have just taken my GS1000G 1980 BS34SS carbs apart. They are actually in a surprisingly good condition and I have replaced all o-rings and checked the jet sizes. As #3 cylinder was running a bit rich I expected some problem with that carb or intake and found that it had a pilot jet #45 where the other 3 are #40. I am assuming this would cause the rich running at cruise and below.

    The bike has standard stock aircleaner with4 into one header with a fairly freeflow silencer (all unknown make) and ran fairly well,
    Main jets are 110
    Jet needles are 5D57 at 3rd notch
    Pilot jet under rubber plug #40 (#3 = #45)
    Pilot air jet 160
    Pilot mixture screws were all set at 1 3/4 turns out

    As said #3 plug was burning a black at cruising speed and I used to get a bit of popping on decel after high revs, but have not checked or replaced the header seals after removing it a couple of times.

    Are the main jets within useful range as the GS1000E shows #107.5 and the GS1000G shows #115 and I have #110?

    I have to order one #40 pilot from the USA and might as well order the mains if they are not right. (Wonder who will be prepared to ship such a small part all the way to the RSA?)
    If anyone can advise here I will appreciate
    Thanks in advance
  • trippivot
    Forum Sage
    Past Site Supporter
    • Aug 2006
    • 2815
    • Des Moines , IA

    #2
    the #40 might help for smoother bypass transition and similar mixture screw settings for all 4 carbs.
    Or you could lower the #3 needle 1 clip position to relieve the improper pilot jet on that cylinder for 1/8 throttle~1/4 throttle opening for riding instead of ordering jets. But not many people like to have different settings in their carbs, sometimes you have to address 1 cylinder differently than the others as needed for rideability.

    with a open exaust muffler I'd go possibly bigger than 115 all the way to 127.5 on mains. A plug chop test needed to verify what the bike likes

    the popping is a lean condition on decelleration remedied by enrichening the idle mixture screw. those carbs didn't have a deacceleration valve and run on diaphram like other carbs of that era.

    I have all jets you may need let me know if you need more assistance and shipping.... trippivot@hotmail.com
    SUZUKI , There is no substitute

    Comment

    • Guest

      #3
      You can also pop on a rich condition. The wasted spark burns the unburnt fuel in the cylinder.

      Comment

      • Matchless

        #4
        Thanks for the reply. I will contact you.

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