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  • Carb or petcock

    I took Brutus out for a spin yesterday to warm him up so I could dump the oil. 10 miles into the ride he started running rough and I mean I did not think I was going to make it back home 2 miles to go, but I did barely!

    Brainstormed for awhile then went back to start him,after letting him run for awhile I noticed 3 and 4 header pipes were cold. 1 was screaming HOT and 2 seemed not as hot as 1 but still too hot to touch.

    Today I went to start him after switching right petcock to prime and he ran fine until I noticed the WOT. After closing it and switching petcock back to on, had the same rough running. All four headers were hot but smoke was coming from the bottom of 3rd and 4th header at the first junction connection. Smelled like burning oil.

    Am I in trouble again?

    p.s. I took him out the day before, and for some unknown reason I decided to feel the pressure coming out of the exhaust and noticed the right side was not as powerful as the left. I dismissed it because after he warmed up I checked again and both seemed to have equal pressure.
    BAMN!

    '81 XS1100H "Brutus"

  • #2
    If 3 and 4 were not getting enough fuel they may have been dumping unburned gas and oil into the exhaust, and with it on prime and getting hot that would start to burn out. It sounds to me like the petcock is not working right and not opening with vacuum. You may have a rebuild kit in your future, after which if done right things should work fine (I'm talking petcock rebuild). BTW, if you suspect at any time that you have ANY gas in your oil, (I thought you had said that at one time, but I might be mis-remembering) never ride the bike to warm it up before changing it, just change it cold, there is too much chance of damage to bearings if there is ANY gas in the oil, it's just not worth the chance, you can warm it up with no load, but if you suspect gas in the oil, or have ANYTHING in the oil that thins it, don't put ANY load on the engine whatsoever until you change the oil.
    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.

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    • #3
      Originally posted by cywelchjr View Post
      If 3 and 4 were not getting enough fuel they may have been dumping unburned gas and oil into the exhaust, and with it on prime and getting hot that would start to burn out. It sounds to me like the petcock is not working right and not opening with vacuum. You may have a rebuild kit in your future, after which if done right things should work fine (I'm talking petcock rebuild). BTW, if you suspect at any time that you have ANY gas in your oil, (I thought you had said that at one time, but I might be mis-remembering) never ride the bike to warm it up before changing it, just change it cold, there is too much chance of damage to bearings if there is ANY gas in the oil, it's just not worth the chance, you can warm it up with no load, but if you suspect gas in the oil, or have ANYTHING in the oil that thins it, don't put ANY load on the engine whatsoever until you change the oil.
      No gas in oil as far as I can tell.
      If the petcock is vacuum operated how can I test it to be sure that's the problem?
      Last edited by Nubian; 06-30-2011, 01:49 PM.
      BAMN!

      '81 XS1100H "Brutus"

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      • #4
        I also just recently read where someone was also having petcock trouble and was going to tee off the other side for a temporary bypass. Will that work? Will that one line deliver enough fuel for all four carbs?
        BAMN!

        '81 XS1100H "Brutus"

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