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Main Jet/Pilot Jet Recommendations For Mac 4 into 1 Exhaust on 82 GS1100 GK?

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    Main Jet/Pilot Jet Recommendations For Mac 4 into 1 Exhaust on 82 GS1100 GK?

    Anyone have recommendations for Main Jet/Pilot Jet changes when switching to a Mac 4 into 1 Exhaust on 82' GS1100 GK? Thinking of bumping Mains Jets from stock 115 to 117.5 not sure about Pilot.

    Thanks!!
    Dan

    #2
    With the MAC exhaust, you may find that you need no changes at all. The stock exhaust actually flowed surprisingly well. Intake changes seem to make a bigger difference.

    1980 GS1000GT (Daily rider with a 1983 1100G engine)
    1998 Honda ST1100 (Daily long distance rider)
    1982 GS850GLZ (Daily rider when the weather is crap)

    Darn, with so many daily riders it's hard to decide which one to jump on next.

    JTGS850GL aka Julius

    GS Resource Greetings

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      #3
      Intake changes meaning? Air Filter? Running K&N with stock air box.
      Thanks!

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        #4
        Originally posted by deepseadiver84 View Post
        Anyone have recommendations for Main Jet/Pilot Jet changes when switching to a Mac 4 into 1 Exhaust on 82' GS1100 GK? Thinking of bumping Mains Jets from stock 115 to 117.5 not sure about Pilot.

        Thanks!!
        Dan
        Stock pilot jets will be fine, you may have to turn the mixture screws out 0.25-0.5 turns beyond stock. Mains will need at most 2-3 steps with a Mac system, as JTGS850GL says the stock system isn't that bad and the Mac system isn't that free-flowing. Before changing jets I would tweak the mixture screws, see how it runs and check the plugs. If everything is ok, leave it at that.


        Mark
        1982 GS1100E
        1998 ZX-6R
        2005 KTM 450EXC

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          #5
          If the MAC has the "street" baffle, probably no changes needed at all.

          If you have the "competition baffle", probably best to add about three sizes to the mains. The stock pilots will be fine.

          How can you tell if you have a "street" or "competition" baffle? It's actually quite easy. Look into the end of the pipe or stick a broom handle in. If it only goes a few inches (less than a foot), you have a street baffle. There will also be no perforations on the pipe. If it goes in more than that, you have the straight-through competition baffle, and the pipe will be perforated.

          .
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            #6
            Thank you all for your input! I just picked up (4) 117.5 main's at Sudco before I read your posts. I am running a Mac with baffle in place. John at SUDCO recommended just going up 1 step as well with the Mac pipes. I'll try them out and adjust mixture screws as necessary.
            Dan

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