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weak springs, to short cable or ?????

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  • #1

    weak springs, to short cable or ?????

    Hey guys, I finally got this 81 I picked up started up and running, one small problem. The throttle doesn't seem to close fully by its self. What I mean is that if I adjust the main idle screw "out" far enough to get around 1000rpm idle then when I rev it and let go it will return to around 1500 - 2000, if I take a long screw driver and gently push down on the linkage the idle will then return to where I set it, but then slowly creep back up once the pressure is removed.

    When I had the carbs off for cleaning the butterfly on #4 was initially stuck closed, but after freeing it with a little heat and PB blaster everything seemed to work smooth and free. Also the throttle cable on the bike seemed to work very easily and visually looks to be new.

    I have checked that the linkage isn't hanging up on any of the clamps for the carb boots, been there and done that before.

    As you can imagine this makes it hard to get a perfect synch and idle mix adjustment.

    Anyone else ever had a similar problem?
    1979 xs1100 Special -
    Stock air box/K&N Filter, MAC 4-2 exhaust, Bad-Boy Air horn, TC fuse box, Windshield, Soft bags, Vetter Fairing, Blinkers->Run/Turn/Brake Lights, Headlight Modulator, hard wire GPS power

    Short Stack - 1981 xs1100 Standard - lowered for SWMBO.

    Originally posted by fredintoon
    Goes like a train, corners like a cow, shifts like a Russian tractor, drinks like a fish, you are gonna love it.
    My Bike:
    [link is broken]
    Tags: None
  • #2
    Originally posted by psycoreefer View Post
    Hey guys, I finally got this 81 I picked up started up and running, one small problem. The throttle doesn't seem to close fully by its self. What I mean is that if I adjust the main idle screw "out" far enough to get around 1000rpm idle then when I rev it and let go it will return to around 1500 - 2000, if I take a long screw driver and gently push down on the linkage the idle will then return to where I set it, but then slowly creep back up once the pressure is removed.

    When I had the carbs off for cleaning the butterfly on #4 was initially stuck closed, but after freeing it with a little heat and PB blaster everything seemed to work smooth and free. Also the throttle cable on the bike seemed to work very easily and visually looks to be new.

    I have checked that the linkage isn't hanging up on any of the clamps for the carb boots, been there and done that before.

    As you can imagine this makes it hard to get a perfect synch and idle mix adjustment.

    Anyone else ever had a similar problem?
    You know, that could actually be the sync being way out. Have you tried just doing a blind sync on it without adjusting the mix first? You may found as I did on mine on the first sync that one carb has WAY less vacuum and the bike will die when you adjust it, and you adjust the idle speed and continue, then do the idle mix and then back through the sync, and then lather, rinse and repeat as needed.

    Then again I could be totally wrong, it wouldn't be the first time, and I'm sure it won't be the last either.
    Cy

    1980 XS1100G (Brutus) w/81H Engine
    Duplicolor Mirage Paint Job (Purple/Green)
    Vetter Windjammer IV
    Vetter hard bags & Trunk
    OEM Luggage Rack
    Jardine Spaghetti 4-2 exhaust system
    Spade Fuse Box
    Turn Signal Auto Cancel Mod
    750 FD Mod
    TC Spin on Oil Filter Adapter (temp removed)
    XJ1100 Front Footpegs
    XJ1100 Shocks

    I was always taught to respect my elders, but it keeps getting harder to find one.

    Comment

    • #3
      Yeah, I did a bench synch when I had the carbs off, put them on and added gas and it fired right up, up to about 3k that is. Lowered the idle, on bike synch at 2k as that is where it wants to hover without the mentioned pressure.

      Looked really good, only off by about 1 tick on my gauge, adjusted to the same vacuum at 2k. Really that should be the same at idle as well, its the idle mix which is impossible to adjust at 2k.

      My usual process is idle mix -> synch -> idle mix -> re-check synch. But thats starting with carbs that were close to proper synch to begin with. These I started with a synch because I had no Idea where they'd be.

      I'm thinking when I get home I'll pull the cable off the linkage and see what happens, that should eliminate a too short or bound up cable as the culprit.
      1979 xs1100 Special -
      Stock air box/K&N Filter, MAC 4-2 exhaust, Bad-Boy Air horn, TC fuse box, Windshield, Soft bags, Vetter Fairing, Blinkers->Run/Turn/Brake Lights, Headlight Modulator, hard wire GPS power

      Short Stack - 1981 xs1100 Standard - lowered for SWMBO.

      Originally posted by fredintoon
      Goes like a train, corners like a cow, shifts like a Russian tractor, drinks like a fish, you are gonna love it.
      My Bike:
      [link is broken]

      Comment

      • #4
        I guess the first thing I would suspect would be a gummed up cable!

        Deny
        1978 XS1100E - The TimeMachine
        1980 XS850 Special - Little Mo

        Comment

        • #5
          Originally posted by DenyP View Post
          I guess the first thing I would suspect would be a gummed up cable!
          That was my thought... If you can push it down manually, and it stays, it's not the sync of the carbs. Clean and lube the cable, and you should have a much better response.
          1980 XS850SG - Sold
          1981 XS1100LH Midnight Special (Sold) - purchased 9/29/08
          Fully Vetterized and Dynojet Kit added, Heated Grips, Truck-Lite LED headlight, Accel Coils, Irridium plugs, TKAT Fork Brace, XS850LH Final Drive & Black SS Brake lines from Chacal.
          Here's my web page devoted to my bike! XS/XJ User's Manuals there, and the XJ1100 Service Manual and both XS1100 Service manuals (free download!).

          Whether you think you can, or you think you cannot - You're right.
          -H. Ford

          Comment

          • #6
            Originally posted by psycoreefer View Post
            Hey guys, I finally got this 81 I picked up started up and running, one small problem. The throttle doesn't seem to close fully by its self. What I mean is that if I adjust the main idle screw "out" far enough to get around 1000rpm idle then when I rev it and let go it will return to around 1500 - 2000, if I take a long screw driver and gently push down on the linkage the idle will then return to where I set it, but then slowly creep back up once the pressure is removed.
            Originally posted by CatatonicBug View Post
            That was my thought... If you can push it down manually, and it stays, it's not the sync of the carbs. Clean and lube the cable, and you should have a much better response.
            It doesn't thats what gets me, its like the vibration of the running motor opens the carbs back up after I remove the pressure.

            I will clean and lube the cable though, never hurts....
            1979 xs1100 Special -
            Stock air box/K&N Filter, MAC 4-2 exhaust, Bad-Boy Air horn, TC fuse box, Windshield, Soft bags, Vetter Fairing, Blinkers->Run/Turn/Brake Lights, Headlight Modulator, hard wire GPS power

            Short Stack - 1981 xs1100 Standard - lowered for SWMBO.

            Originally posted by fredintoon
            Goes like a train, corners like a cow, shifts like a Russian tractor, drinks like a fish, you are gonna love it.
            My Bike:
            [link is broken]

            Comment

            • #7
              Originally posted by psycoreefer View Post
              It doesn't thats what gets me, its like the vibration of the running motor opens the carbs back up after I remove the pressure.
              The spring on the linkage should be PLENTY strong to overcome the vacuum of the carbs. I would double-check that return spring while you're in there, and make sure it's working properly. My fingers get sore holding the butterfies open on mine, because the spring is so strong.
              1980 XS850SG - Sold
              1981 XS1100LH Midnight Special (Sold) - purchased 9/29/08
              Fully Vetterized and Dynojet Kit added, Heated Grips, Truck-Lite LED headlight, Accel Coils, Irridium plugs, TKAT Fork Brace, XS850LH Final Drive & Black SS Brake lines from Chacal.
              Here's my web page devoted to my bike! XS/XJ User's Manuals there, and the XJ1100 Service Manual and both XS1100 Service manuals (free download!).

              Whether you think you can, or you think you cannot - You're right.
              -H. Ford

              Comment

              • #8
                resolution...

                well, for all future readers it was too short cable. Unhooked the cable from the carbs today and idle was back to normal, no wonder the PO's were having such trouble getting it to run right. Luckily I had a spare cable for my other xs in the "parts" bin so I just switched them out.

                Idle is set at 1100, carbs are synched and mixtures adjusted. Idles smooth and steady.
                1979 xs1100 Special -
                Stock air box/K&N Filter, MAC 4-2 exhaust, Bad-Boy Air horn, TC fuse box, Windshield, Soft bags, Vetter Fairing, Blinkers->Run/Turn/Brake Lights, Headlight Modulator, hard wire GPS power

                Short Stack - 1981 xs1100 Standard - lowered for SWMBO.

                Originally posted by fredintoon
                Goes like a train, corners like a cow, shifts like a Russian tractor, drinks like a fish, you are gonna love it.
                My Bike:
                [link is broken]

                Comment

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