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which main jets for high altitude?

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    #1

    which main jets for high altitude?

    Greetings,
    I've just purchased a 1980 GS750E (Mikuni BS32SS carbs) with only 7400 original miles which is running really rich. I've taken the carbs apart to clean and install new main jets and I am looking for suggestions as to which jets I should get for a bike which will mostly be ridden above 7000 feet. The jets are stamped with what appears to be 735. Can this be right? The bike comes from sea level and I'm pretty sure those are the stock jets. What should I replace them with and do I also need to replace the jet needles?
    Thanks in advance,
    Jerry
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    #2
    I hope they don't say 735 .

    What have you done to the bike so far?
    Have you cleaned the carbs with a good soak and ALL the orings replaced?
    Stock jets MAY be a bit large for 7000 feet HOWEVER, I doubt that it has much if anything to do with your current 'rich' condition.
    Stock air box with filter NOT OVER OILED?
    Stock pipes?
    Petcock test done yet?

    Welcome to the GSR. We'll get the bike running correctly, not a problem.

    Comment

      #3
      Maybe 135.
      Stock main jet is a 112.5. At that elevation I'd go with a 110 mikuni main jet. If you ever plan on riding at sea level I'd keep it stock.
      1983 GS 1100E w/ 1230 kit, .340 lift Web Cams, Ape heavy duty valve springs, 83 1100 head with 1.5mm oversized SS intake valves, 1150 crank, Vance and Hines 1150 SuperHub, Star Racing high volume oil pump gears, 36mm carebs Dynojet stage 3 jet kit, Posplayr's SSPB, Progressive rear shocks and fork springs, Dyna 2000, Dynatek green coils and Vance & Hines 4-1 exhaust.
      1985 GS1150ES stock with 85 Red E bodywork.

      Comment

        #4
        "I hope they don't say 735 .

        What have you done to the bike so far?
        Have you cleaned the carbs with a good soak and ALL the orings replaced?
        Stock jets MAY be a bit large for 7000 feet HOWEVER, I doubt that it has much if anything to do with your current 'rich' condition.
        Stock air box with filter NOT OVER OILED?
        Stock pipes?
        Petcock test done yet?

        Welcome to the GSR. We'll get the bike running correctly, not a problem."

        It sure looks like they say 735 but I didn't think that could be right, either. I failed to mention the after market Vance and Hines pipes. Also, I have not really done a rebuild as far as changing o rings and such and am relying heavily on a mech friend for guidance since, carb-wise, I'm pretty much a neophyte. He says everything looks great but that the jets need to be replaced. It's possible that the after market air filter has been over-oiled, certainly something to look into and I have NOT done a petcock test yet but I have the feeling I'll be doing that soon.

        I haven't really done too much to the bike yet just sorted out some electrical issues and have ordered a new stator according to the results of some diagnostic work.

        Thanks again for taking the time to help me out, it is GREATLY appreciated.

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