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  • #1

    Fast idle...

    I have her back together, the carbs are synched, she leaks oil from a couple of new places, and another issue has come up (yeah, I'm shocked, too).

    The master idle adjuster is opened all the way, no longer in contact with the throttle, and the idle hangs around 1900rpm when warm and no choke.

    Changes from when she ran: new head gasket, new #3 intake valve, carb floats adjusted to spec (she ran fine for years with the floats set very high/rich), idle screws 1.5 out, Iridium plugs, numerous curse words and violent oaths.
    "Time is the greatest teacher; unfortunately, it kills all of its students."
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  • #2
    I am willing to bet that your throttle cable is hung up somewhere or it is not properly seated in the little hold notch on the top side of the carbs.
    Nathan
    KD9ARL

    μολὼν λαβέ

    1978 XS1100E
    K&N Filter
    #45 pilot Jet, #137.5 Main Jet
    OEM Exhaust
    ATK Fork Brace
    LED Dash lights
    Ammeter, Oil Pressure, Oil Temp, and Volt Meters
    Green Monster Coils
    SS Brake Lines
    Vision 550 Auto Tensioner

    In any moment of decision the best thing you can do is the right thing, the next best thing is the wrong thing, and the worst thing you can do is nothing.

    Theodore Roosevelt

    Comment

    • #3
      I thought of that, but no dice...there's even a bit of slack. Would running leaner increase the idle? That doesn't seem likely.
      "Time is the greatest teacher; unfortunately, it kills all of its students."

      Comment

      • #4
        Have you syncronized the carbs?
        Greg

        Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid.”

        ― Albert Einstein

        80 SG Ol' Okie;79 engine & carbs w/pods, 45 pilots, 140 mains, Custom Mac 4 into 2 exhaust, ACCT,XS850 final drive,110/90/19 front tire,TKat fork brace, XS750 140 MPH speedometer, Vetter IV fairing, aftermarket hard bags and trunk, LG high back seat, XJ rear shocks.

        The list changes.

        Comment

        • #5
          I have synched the carbs.
          "Time is the greatest teacher; unfortunately, it kills all of its students."

          Comment

          • #6
            A hanging throttle or carbs out of sync are about the only things that'll cause a high idle. A vacuum leak(s) could cause it under the right conditions but it's not very likely with a carbureted engine.
            Greg

            Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid.”

            ― Albert Einstein

            80 SG Ol' Okie;79 engine & carbs w/pods, 45 pilots, 140 mains, Custom Mac 4 into 2 exhaust, ACCT,XS850 final drive,110/90/19 front tire,TKat fork brace, XS750 140 MPH speedometer, Vetter IV fairing, aftermarket hard bags and trunk, LG high back seat, XJ rear shocks.

            The list changes.

            Comment

            • #7
              JAT......disconnect the throttle cable frome the carbs and see if it makes a difference.
              Greg

              Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid.”

              ― Albert Einstein

              80 SG Ol' Okie;79 engine & carbs w/pods, 45 pilots, 140 mains, Custom Mac 4 into 2 exhaust, ACCT,XS850 final drive,110/90/19 front tire,TKat fork brace, XS750 140 MPH speedometer, Vetter IV fairing, aftermarket hard bags and trunk, LG high back seat, XJ rear shocks.

              The list changes.

              Comment

              • #8
                Carbs

                before you put the carbs back on the bike did you do a visual check to see if all 4 close completly and at the same time? If they all will close completly with the idle screw out, then you have a vacuum leak with or without a fuel bleed through the choke linkage JIMHO
                1979 XS1100 Special (Mad Max, OEM) Current
                1980 XS1100 Special
                1990 V Max
                1982 KZ750 LTD Twin
                1986 700 FZR Yamaha Fazer (faster then expected)
                1979 XS750 Special (my 1st Special)
                1974 CB750-Four



                Past/pres Car's
                1961 Catalina 389/1970 Torino GT 351/1967GTO 12to1 comp./ Roller cam/ T-10/ 456 gear/Tri-power/1967 GTO 400, 1969 Camaro, 1968 Z28, 2001 BMW M Roadster 0 to 60 in 4.5 sec. Jaguar XK8

                Comment

                • #9
                  Originally posted by LoHo View Post
                  I have synched the carbs.
                  Bench sync, or on the bike while it's running? High idle will be pretty normal with a bench sync....
                  Fast, Cheap, Reliable... Pick any two

                  '78E original owner - resto project
                  '78E ???? owner - Modder project FJ forks, 4-piston calipers F/R, 160/80-16 rear tire
                  '82 XJ rebuild project
                  '80SG restified, red SOLD
                  '79F parts...
                  '81H more parts...

                  Other current bikes:
                  '93 XL1200 Anniversary Sportster 85RWHP
                  '86 XL883/1200 Chopper
                  '82 XL1000 w/1450cc Buell, Baker 6-speed, in-progress project
                  Cage: '13 Mustang GT/CS with a few 'custom' touches
                  Yep, can't leave nuthin' alone...

                  Comment

                  • #10
                    +1

                    Originally posted by crazy steve View Post
                    Bench sync, or on the bike while it's running? High idle will be pretty normal with a bench sync....
                    +1 Steve, IMHO bench is just to get the bike running again, worthless for anything else
                    1979 XS1100 Special (Mad Max, OEM) Current
                    1980 XS1100 Special
                    1990 V Max
                    1982 KZ750 LTD Twin
                    1986 700 FZR Yamaha Fazer (faster then expected)
                    1979 XS750 Special (my 1st Special)
                    1974 CB750-Four



                    Past/pres Car's
                    1961 Catalina 389/1970 Torino GT 351/1967GTO 12to1 comp./ Roller cam/ T-10/ 456 gear/Tri-power/1967 GTO 400, 1969 Camaro, 1968 Z28, 2001 BMW M Roadster 0 to 60 in 4.5 sec. Jaguar XK8

                    Comment

                    • #11
                      Carbs were synched on the bike.
                      "Time is the greatest teacher; unfortunately, it kills all of its students."

                      Comment

                      • #12
                        Originally posted by LoHo View Post
                        Carbs were synched on the bike.
                        At 1900 RPM?
                        Greg

                        Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid.”

                        ― Albert Einstein

                        80 SG Ol' Okie;79 engine & carbs w/pods, 45 pilots, 140 mains, Custom Mac 4 into 2 exhaust, ACCT,XS850 final drive,110/90/19 front tire,TKat fork brace, XS750 140 MPH speedometer, Vetter IV fairing, aftermarket hard bags and trunk, LG high back seat, XJ rear shocks.

                        The list changes.

                        Comment

                        • #13
                          Well, not exactly. It ran rougher at lower rpm until they were all even. As I synched 1/2 to 3/4, the rpms climbed and stuck around 18-1900.
                          "Time is the greatest teacher; unfortunately, it kills all of its students."

                          Comment

                          • #14
                            I'm going to go out on a limb and say that's where your problem is. You can't properly sync carbs above about 800RPM.
                            Greg

                            Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid.”

                            ― Albert Einstein

                            80 SG Ol' Okie;79 engine & carbs w/pods, 45 pilots, 140 mains, Custom Mac 4 into 2 exhaust, ACCT,XS850 final drive,110/90/19 front tire,TKat fork brace, XS750 140 MPH speedometer, Vetter IV fairing, aftermarket hard bags and trunk, LG high back seat, XJ rear shocks.

                            The list changes.

                            Comment

                            • #15
                              I believe you...but since the master adjuster is fully open, how do I get the rpms down to do it properly?
                              "Time is the greatest teacher; unfortunately, it kills all of its students."

                              Comment

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