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Engine revs down very slowly after you roll off the throttle.

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  • Engine revs down very slowly after you roll off the throttle.

    I've been doing some work to my 79 XS1100 I picked up a while back. I have almost all of the kinks worked out except one. When riding the bike, when I go to shift to the next gear, I roll of the throttle and the engine holds for several seconds before it starts very very slowly keep back towards idle. My throttle cable isn't hanging. My first thought was that I probably have a vacuum leak everywhere. I've looked around the carb boots, and they look worn but alright. As far as vacuum lines are concerned, I only have one; the line for the vacuum advance. All of the other ports are caped, and I don't have the vacuum control fuel valve. Can you guys think of anything I might check?

  • #2
    Carbs might be out of sync and/or vacuum leaks between carb boots and engine.
    2H7 (79) owned since '89
    3H3 owned since '06

    "If it ain't broke, modify it"

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    • #3
      How does it idle?? It does sound as though the carbs are out of sync.
      The Old Tamer
      _________________________
      1979 XS1100SF (The Fire Dragon)
      1982 650 Maxim (The Little Dragon)
      another '82 650 Maxim (Parts Dragon)
      1981 XS1100SH (The Black Dragon)

      If there are more than three bolts holding it on there, it is most likely a very important part!

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      • #4
        And maybe lean...

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        • #5
          I'm thinking leaky boots, mine did the same thing, found the boots were sucking air casing a lean condition and holding the revs up for an extended period of time. have a nice day and ride safe
          I am the Lorax, I speak for the Trees

          '80 XS1100 SG (It's Evil, Wicked, Mean & Nasty)

          '79 XS1100 F R (IL Barrachino)

          '00 Suzuki Intruder 1400 (La Soccola)

          '77 KZ400s (La Putana)

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          • #6
            And have a better look at thos caps. Mine were hard and didn't seal, even though they looked intact.
            "Time is the greatest teacher; unfortunately, it kills all of its students."

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            • #7
              I took a further look at the carbs, and three of the four mixture screw tips were broke off. I'm going to rebuild the carbs this weekend and put on a new pair of boots. One of my boots has already been rtv ed a few times. Thanks for all of the responses. I'll post back with my results.

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              • #8
                Good Luck with those broken tips!! Seriously I have had three and have never been able to get them out with out drilling.
                "Beware of any man that owns a pig farm"
                "Hence the meaning of the Saying,.. As greedy as a pig"
                79 XS1100 modified standard
                Chain Drive, Monoshock,extendend hand built swingarm, 200 rear
                pod filters,150 mains,45 pilots
                straight pipe 4-2 exhaust
                new to me 05 Kawasaki zxr12r man does she fly
                Owned 83 Honda V65 Magna
                Owned 02 Vstar 650 classic
                owned 85 Honda Shadow VT 700C

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                • #9
                  Originally posted by audijunky
                  Good Luck with those broken tips!! Seriously I have had three and have never been able to get them out with out drilling.
                  A sewing needle such as the type used for canvas work, some gentle paitent tapping to drive the tip back out the way it went in.

                  Ask me how I know
                  Trying not to offend since Aug 28, 2010

                  Disclaimer: I am an idiot. Pay no attention to the man behind the curtain.
                  Owner of:
                  1979 XS1100F (The Pig)
                  140 mains
                  45 pilot jets
                  Floats at 24mm
                  Running Rich

                  "Arrogant, delusional tyrants can't be stopped by earnest words and furrowed brows. Action, strong bold action coming from a position of strength and determination, is the only effective deterrent." -Mitt Romney

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                  • #10
                    Running lean, leaks in the intake system or dirty slow returning carb slides Also check the cable for very smooth operation.
                    Rob
                    KEEP THE RUBBER SIDE DOWN

                    1978 XS1100E Modified
                    1978 XS500E
                    1979 XS1100F Restored
                    1980 XS1100 SG
                    1981 Suzuki GS1100
                    1983 Suzuki GS750S Katana
                    1983 Honda CB900 Custom

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                    • #11
                      Originally posted by rman


                      A sewing needle such as the type used for canvas work, some gentle paitent tapping to drive the tip back out the way it went in.

                      Ask me how I know
                      I too, have tried everyway possible, mechanic picks, sewing needle, easyout, you name it and I tried it.
                      guess I just dont got the patience

                      I wonder if brass melts at a lower temp than aluminium
                      "Beware of any man that owns a pig farm"
                      "Hence the meaning of the Saying,.. As greedy as a pig"
                      79 XS1100 modified standard
                      Chain Drive, Monoshock,extendend hand built swingarm, 200 rear
                      pod filters,150 mains,45 pilots
                      straight pipe 4-2 exhaust
                      new to me 05 Kawasaki zxr12r man does she fly
                      Owned 83 Honda V65 Magna
                      Owned 02 Vstar 650 classic
                      owned 85 Honda Shadow VT 700C

                      Comment


                      • #12
                        Vaccuum leak (especially the caps) and carb sync have already been mentioned. Mine did the same thing until I addressed those areas.

                        You should also check the routing of your throttle cable. Make sure it passes through all the right clips and that the end of it is seated properly. I seem to remember this being a culprit one time when mine wasn't running exactly right. As it's necessary to disengage the cable to remove the carbs, it's easy to forget about it on re-install.

                        Also a little bit of light with rust preventative (I use 3 in 1 oil) down the length of the throttle cable itself can help. The cable can stick to the interior walls of the cable sheath. It's a good maintenance practice anyways and always rewards you with a "quicker" feel on the throttle hand.

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                        • #13
                          Yeah, so I've gone to rebuild the carb. I get the entire carb apart. I go to unscrew the pilot jet, and it's totally stripped and seized. Any ideas on a good way to get it out? Has anyone tried extractors?

                          I'm really starting to dislike the previous owner of this bike. I've fixed tons of used cars and a few bike, and I've never seen anything with this many botched repair jobs

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                          • #14
                            Fixed

                            So I went to rebuild the carbs, and they were total junk. The person that attempted to rebuild them before had no clue; everything was way over torqued and stripped out. I ended getting a rebuild set on ebay.

                            No more problems, runs great now. Thanks everyone for the input.

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