Fast idle...

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  • LoHo
    XS-XJ Guru
    • Sep 2002
    • 1341
    • Fresno, CA
    #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."
    Tags: None
    • natemoen
      Master of XSology
      • May 2010
      • 8640
      • Fargo
      #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
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      Ammeter, Oil Pressure, Oil Temp, and Volt Meters
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      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.

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        Comment

        • LoHo
          XS-XJ Guru
          • Sep 2002
          • 1341
          • Fresno, CA
          #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

            • BA80
              Doctor of XSology
              • Oct 2010
              • 9980
              • Tulsa, Ok
              #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

                • LoHo
                  XS-XJ Guru
                  • Sep 2002
                  • 1341
                  • Fresno, CA
                  #5
                  I have synched the carbs.
                  "Time is the greatest teacher; unfortunately, it kills all of its students."

                    Comment

                    • BA80
                      Doctor of XSology
                      • Oct 2010
                      • 9980
                      • Tulsa, Ok
                      #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

                        • BA80
                          Doctor of XSology
                          • Oct 2010
                          • 9980
                          • Tulsa, Ok
                          #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

                            • XS1100_OEM4ME
                              XS-XJ Guru
                              • Mar 2009
                              • 1619
                              • Fort Myers, Florida
                              #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

                                • crazy steve
                                  XS-XJ Guru MODERATOR
                                  • Jan 2009
                                  • 7932
                                  • Beautiful outer Yelm, WA
                                  #9
                                  Originally posted by LoHo
                                  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

                                    • XS1100_OEM4ME
                                      XS-XJ Guru
                                      • Mar 2009
                                      • 1619
                                      • Fort Myers, Florida
                                      #10
                                      +1

                                      Originally posted by crazy steve
                                      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

                                        • LoHo
                                          XS-XJ Guru
                                          • Sep 2002
                                          • 1341
                                          • Fresno, CA
                                          #11
                                          Carbs were synched on the bike.
                                          "Time is the greatest teacher; unfortunately, it kills all of its students."

                                            Comment

                                            • BA80
                                              Doctor of XSology
                                              • Oct 2010
                                              • 9980
                                              • Tulsa, Ok
                                              #12
                                              Originally posted by LoHo
                                              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

                                                • LoHo
                                                  XS-XJ Guru
                                                  • Sep 2002
                                                  • 1341
                                                  • Fresno, CA
                                                  #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

                                                    • BA80
                                                      Doctor of XSology
                                                      • Oct 2010
                                                      • 9980
                                                      • Tulsa, Ok
                                                      #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

                                                        • LoHo
                                                          XS-XJ Guru
                                                          • Sep 2002
                                                          • 1341
                                                          • Fresno, CA
                                                          #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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