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  • #1

    XJ carb problems?

    All in all, My XJ runs great, but. When I first start it, #1's exhaust pipe stays cold until I start riding it (I know, the idle circuit dirty/blocked). But, from then on, when I let it idle the pipe stays hot. Even starting it an hour or so later, it (#1 pipe) will immediately get hot at an idle.

    I also have a (mostly) mild after fire popping out of the left muffler when backing off to a closed throttle from about 3000 to 3500 rpm's.

    Exhaust is stock and the jetting is factory. And I would bet money the carb passages are all (are were) clean.

    I just this evening started on a second tank of gas with seafoam in it. Saw no results/improvements with the first.

    Louis
    "There is no mechanical problem so difficult that it cannot be overcome by
    brute strength and ignorance" And possibly some Mouse Milk!
    '82 XJ1100J
    LED Dir and running lights
    LED Tail/Brake lights (4) one flashing
    Modulated H/L
    PIAA Driving lights
    YICS Eliminated
    750 FD

    Yamaha Factory X-1 Fairing and Luggage
    Tags: None
  • #2
    Re: XJ carb problems?

    You might try turning out its pilot screw about a quarter turn to see what happens. Mixtures get richer as the head heats-up.

    Originally posted by lsippell
    All in all, My XJ runs great, but. When I first start it, #1's exhaust pipe stays cold until I start riding it (I know, the idle circuit dirty/blocked). But, from then on, when I let it idle the pipe stays hot. Even starting it an hour or so later, it (#1 pipe) will immediately get hot at an idle.
    Skids (Sid Hansen)

    Down to one 1978 E. Stock air box with K&N filter, 81H pipes and carbs, 8500 feet elevation.

    Comment

    • #3
      Hey Louis,

      Have you checked your intakes for leaks? Could be a very small crack/leak that prevents a good vacuum when totally cold, but once the engine warms up, things expand and seal enough to not leak, not run so lean? Like where the intakes mount to the engine, not necessarily the intakes themselves?

      But yeah, it does sound like the pilot circuit. If it's a mild to modest gumming the Sea Foam should dissolve it, but it might take more than one application. How much/many ounces per tank are you putting in? Even though the normal is about 4 ounces per OUR gas tanks, a few have put a whole 16oz can in one. 1/2 can might be advisable?

      When was the last time you actually pulled the carbs and got your hands in there!?
      T.C.
      T. C. Gresham
      81SH "Godzilla" . . .1179cc super-rat.
      79SF "The Teacher" . . .basket case!
      History shows again and again,
      How nature points out the folly of men!

      Comment

      • #4
        I've backed out the pilot jet but that didn't help. Didn't think of the intake since I put new intake boots on it. Will have to check the mounting bolts though. I torque’d them when installing them but that doesn't guarantee anything. As far as the Seafoam, I put a half a can (8 oz.) to a full tank. I guess what I'm doing is procrastinating and trying to avoid pulling the carbs again.

        I just got back from about a 50 mile run over some back roads around here. Sure glad I have that fairing to keep the bugs out of my teeth!

        Louis
        "There is no mechanical problem so difficult that it cannot be overcome by
        brute strength and ignorance" And possibly some Mouse Milk!
        '82 XJ1100J
        LED Dir and running lights
        LED Tail/Brake lights (4) one flashing
        Modulated H/L
        PIAA Driving lights
        YICS Eliminated
        750 FD

        Yamaha Factory X-1 Fairing and Luggage

        Comment

        • #5
          Hey Louis,

          There are recent threads here, including a picture, of the enricher circuit jet. I’ll bet that is your problem, as my SG had the same problem. Hard to start, cold running until it warmed up, then ran fine. I too tried Seafoam, to no avail. Ken Talbot (see his post of 4-06) explained the problem, and posted the picture which showed the jet, way down in the float bowl. In my case, I had to pull off the bank of carbs, since two jets were clogged (no’s 1 & 3). At first, I sprayed carb cleaner through the jets which flowed freely in two bowls, but not 1 & 3. So, I found a thin needle and was able to poke it deep into the float bowl passage and “bore out” the hole in those little jets. Another try with spray cleaner and, voila, it flowed out the passage freely. Re-installed, and it started like new again! Like I said to Ken Talbot, when profusely thanking him, I wish I’d known about that jet years ago. Makes a world of difference!!

          You can probably get the #1 bowl off with out removing the whole bank. Then, just unclog that jet with a needle and see how it works.

          Good luck
          Rick
          '80 SG
          '88 FXR
          '66 Spitfire MK II

          Comment

          • #6
            Here's a thread that shows that float bowl jet!
            http://www.xs11.com/forum/showthread...&threadid=7269
            T.C.
            T. C. Gresham
            81SH "Godzilla" . . .1179cc super-rat.
            79SF "The Teacher" . . .basket case!
            History shows again and again,
            How nature points out the folly of men!

            Comment

            • #7
              Louis:

              TC and Rick are exactly right! I had the same problem on my XJ. #1 & #2 cyl. were cold on start-up and stayed that way for about 45 sec. #2 would get warm first and then #2 about 15 sec. later. Ran great after warm-up. Very frustrating since I had thoght I had triple cleaned the carbs. I had never noticed the enricher circuit in the float bowl before! Cut a a wire from a wire brush (more flexable) cleaned the circuit and flushed with Chemtool carb cleaner. No more problem. Also, don't forget to sync the carbs. BIG improvment.

              Rob
              maxim4rob

              Comment

              • #8
                The enricher circuit jets were clean when I reassembled the carbs. Rick, I remember reading about your problems right after I assembled mine and became slightly concerned because one of mine is probably too rich since I was "drilling' crud out from the opening in the bottom of the bowl and felt it drill through something other than crud. I didn't attach to much concern to this because I figured the enricher circuit jet is only used when the 'choke' is on. And a slightly larger opening would only make it richer. Besides, I think this bowl is on #2 or 3.

                In this weather, I only need the 'choke' to start in the morning and then, only for about 10 seconds, then I'm idling without it. Just not burning fuel in #1.

                I'm going to pull the carbs tomorrow evening after the engine cools down and check everything. One thing that keeps popping into my mind is, that though they weren't soaked in carb cleaner, and didn't look too bad at all, maybe the shaft seals are leaking.

                Louis
                "There is no mechanical problem so difficult that it cannot be overcome by
                brute strength and ignorance" And possibly some Mouse Milk!
                '82 XJ1100J
                LED Dir and running lights
                LED Tail/Brake lights (4) one flashing
                Modulated H/L
                PIAA Driving lights
                YICS Eliminated
                750 FD

                Yamaha Factory X-1 Fairing and Luggage

                Comment

                • #9
                  back fire

                  you could have an exhast leak causing the back fire also.
                  1982 XJ 1100
                  going strong after 60,000 miles

                  The new and not yet improved TRIXY
                  now in the stable. 1982 xj11, 18,000miles

                  Comment

                  • #10
                    Does any one have a float bowl for a XJ they would be willing to part with?
                    I have got one with the enrichment jet way over sized. Three of my bowls have a jet size of somewere between .0155 and .0185 while the fourth (on #1 that has been giving me problems) measures .070

                    Thanks in advance.

                    Louis
                    "There is no mechanical problem so difficult that it cannot be overcome by
                    brute strength and ignorance" And possibly some Mouse Milk!
                    '82 XJ1100J
                    LED Dir and running lights
                    LED Tail/Brake lights (4) one flashing
                    Modulated H/L
                    PIAA Driving lights
                    YICS Eliminated
                    750 FD

                    Yamaha Factory X-1 Fairing and Luggage

                    Comment

                    • #11
                      got you covered

                      I've got a float bowl for you... I had the same problems with a couple cylinders being cold... Thought the float bowl jets were plugged so I figured "what could it hurt" to drill them out with a very tiny bit. Well, instead of being plugged, I started to flood those cylinders. I eventually bit the bullet and went to a bike bone yard and picked through the piles of carbs and pulled off 3 float bowls (1 extra just in case). It may be for the wrong side but it will still work - just won't be able to use the drain screw if it's on the wrong side.

                      PM me your address and we'll get'r'done.

                      Tom B.

                      Comment

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