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  • #1

    80 Special idling rough

    I'm having issues with my 80 Special idling rough and popping. The bike had been sitting for the last 4 years but it was running rough as well then. So I just completed a rebuild of the carbs including new kits, de-rusted my tank, & cleaned out the petcocks. While cleaning out the carbs I noticed that it still had 110 main jets in it even though the exhaust was converted over to 4 into 1's. I have the idle mixture screws set at 1.5 turns. After it warms up it seems to run much smoother but there is some cylinder noise. I haven't messed with the cam chain tension yet.

    In anticipation of needing to pull the carbs again I have not installed the airbox or any air filters on the carbs after the rebuild. Could that be changing the behavior of the idle? I also noticed a slow fuel drip (about a drop every 10 to 15 seconds) from the #1 carb but I'm hoping that because of the incline of my driveway.

    Any ideas are appreciated.
    80 XS11 SG
    79 XS750 SF
    74 KZ400
    78 KZ650
    78 KZ750
    Tags: None
  • #2
    With missing of alot of info. IMO, your idle mix IS too lean. Your float levels ARE too high and the compensating is up to this point being done with idle mix. screws. for the lower speed circuit. Also suspect a float hanging in #1 carb rather than a needle and seat leak as the needles are viton tipped. Also, the octy with all the hoses attached isn't working correctly. If you have riden it without the filter housing on, you obviously haven't synced or CORRECTLY set the carbs as this HAS to be done with intake filter/housing in place.
    81H Venturer1100 "The Bentley" (on steroids) 97 Yamaha YZ250(age reducer) 92 Honda ST1100 "Twisty"(touring rocket) Age is relative to the number of seconds counted 'airing' out an 85ft. table-top.

    Comment

    • #3
      Originally posted by CUBuffs View Post
      I'm having issues with my 80 Special idling rough and popping. The bike had been sitting for the last 4 years but it was running rough as well then. So I just completed a rebuild of the carbs including new kits, de-rusted my tank, & cleaned out the petcocks. While cleaning out the carbs I noticed that it still had 110 main jets in it even though the exhaust was converted over to 4 into 1's. I have the idle mixture screws set at 1.5 turns. After it warms up it seems to run much smoother but there is some cylinder noise. I haven't messed with the cam chain tension yet.

      In anticipation of needing to pull the carbs again I have not installed the airbox or any air filters on the carbs after the rebuild. Could that be changing the behavior of the idle? I also noticed a slow fuel drip (about a drop every 10 to 15 seconds) from the #1 carb but I'm hoping that because of the incline of my driveway.

      Any ideas are appreciated.
      Sounds as though you are a bit lean. Sync it and then adjust the idle mixture screws.....repeat...... repeat.......

      Guess what? The airbox won't go back on without removing the carbs again anyway.
      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

      • #4
        Originally posted by CUBuffs View Post
        I'm having issues with my 80 Special idling rough and popping. The bike had been sitting for the last 4 years but it was running rough as well then. So I just completed a rebuild of the carbs including new kits, de-rusted my tank, & cleaned out the petcocks. While cleaning out the carbs I noticed that it still had 110 main jets in it even though the exhaust was converted over to 4 into 1's. I have the idle mixture screws set at 1.5 turns. After it warms up it seems to run much smoother but there is some cylinder noise. I haven't messed with the cam chain tension yet.

        In anticipation of needing to pull the carbs again I have not installed the airbox or any air filters on the carbs after the rebuild. Could that be changing the behavior of the idle? I also noticed a slow fuel drip (about a drop every 10 to 15 seconds) from the #1 carb but I'm hoping that because of the incline of my driveway.

        Any ideas are appreciated.
        My XJ won't hardly start with the air filter out. I would think your mix is way off with the air filter box removed.
        1970? Honda Z50... gone
        1974? Yamaha 100 Enduro... gone
        1974 Honda CB200... gone
        1981 Yamaha Virago 750... gone
        1993 Honda Shadow 1100... gone
        2008 Honda VTX 1800F
        1982 Yamaha XJ1100J w/850 final, Raptor ACCT
        1979 Yamaha XS1100SF "Chewey" Raptor ACCT

        http://www.johnsoldiron.com

        Comment

        • #5
          As said by other members sync and readjust idle mixture do not change any jetting till you get it running smooth. It will run with jetting lean just fine but if you go changing jets all that may do is induce other problems. The mains have little to do with any ruff idle. I am concerned with the leak from #1 carb and you should check for vacume leaks arround boot conections at engine and carbs as this could cause intermittant idle problems.
          To fix the problem one should not make more assumptions than the minimum needed.

          Rodan
          https://www.youtube.com/watch?v=khm6...liHntN91DHjHiS
          1980 G Silverbird
          Original Yamaha Fairfing and Bags
          1198 Overbore kit
          Grizzly 660 ACCT
          Barnett Clutch Springs
          R1 Clutch Fiber Plates
          122.5 Main Jets
          ACCT Mod
          Mac 4-2 Flare Tips
          Antivibe Bar ends
          Rear trunk add-on
          http://s1184.photobucket.com/albums/z329/viperron1/

          Comment

          • #6
            Gas leak

            I discovered gas leaking from the carbs this morning. The petcocks were set to on and yet gas continued to flow without the engine on. Also, the off position would not work. I'm going to order petcock repair kits but is it also possible that the diaphragm may be malfunctioning? I have the vacuum tube from the #2 carb holder attached to the diaphragm and the vacuum advance attached to the #2 carb nipple, is that correct?

            I drained the tank and will examine the float settings while I wait for the petcock kits to arrive.
            80 XS11 SG
            79 XS750 SF
            74 KZ400
            78 KZ650
            78 KZ750

            Comment

            • #7
              Well if you say the petcocks don't work and you have gas coming out of the carbs then you have 3 problems. Petcocks, octy, and float needles/seats. All need to be fixed.

              And yes the octy needs to be hooked to one of the carb holder boots, doesn't matter which one.
              Nathan
              KD9ARL

              μολὼν λαβέ

              1978 XS1100E
              K&N Filter
              #45 pilot Jet, #137.5 Main Jet
              OEM Exhaust
              ATK Fork Brace
              LED Dash lights
              Ammeter, Oil Pressure, Oil Temp, and Volt Meters
              Green Monster Coils
              SS Brake Lines
              Vision 550 Auto Tensioner

              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.

              Theodore Roosevelt

              Comment

              • #8
                mix turns

                on my 81sh with 110's across the board, i reset my mixture screws at 2.5 turns, right where they were before i cleaned them. not sure if the 80 is diff, but u must run it with the air box. without it.........wayyyy too lean.
                Max

                81 XS1100SH Black Beast Mutt
                Kerker 4/1
                stock carbs and air box.
                78 headlite, handle bars,
                1 set of ea-160/85mph guages,
                crash bars, cruise control

                Other 2 Wheelers
                78 XS1100E jet kit, Kerker 4/1, air pods, jet kit-RIP
                94 CBR1000F jet kit,Two Bros pipe, K&N Filter

                Comment

                • #9
                  Originally posted by CUBuffs View Post
                  I discovered gas leaking from the carbs this morning. The petcocks were set to on and yet gas continued to flow without the engine on. Also, the off position would not work. I'm going to order petcock repair kits but is it also possible that the diaphragm may be malfunctioning? I have the vacuum tube from the #2 carb holder attached to the diaphragm and the vacuum advance attached to the #2 carb nipple, is that correct?

                  I drained the tank and will examine the float settings while I wait for the petcock kits to arrive.
                  Did you turn both petcocks off at the same time? If you still have the octy on there gas will continue to flow unless BOTH valves are off. It acts as a T between both sides.
                  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

                  • #10
                    Hmmmm, I can't remember if I turned both petcocks off at the time, but I do remember they both seemed to be in a state of disrepair so I might as well replace them. Has anyone seen a repair kit for the Octo?

                    I will try increasing the idle screw adjustment out a little more after I get the repair kits installed. Thanks.
                    80 XS11 SG
                    79 XS750 SF
                    74 KZ400
                    78 KZ650
                    78 KZ750

                    Comment

                    • #11
                      Georgefix on ebay sells a kit to rebuild the petcocks for the Special, it includes the components to rebuild the OCty as well.
                      Life is what happens while your planning everything else!

                      When your work speaks for itself, don't interrupt.

                      81 XS1100 Special - Humpty Dumpty
                      80 XS1100 Special - Project Resurrection


                      Previously owned
                      93 GSX600F
                      80 XS1100 Special - Ruby
                      81 XS1100 Special
                      81 CB750 C
                      80 CB750 C
                      78 XS750

                      Comment

                      • #12
                        Thanks. I found it.
                        80 XS11 SG
                        79 XS750 SF
                        74 KZ400
                        78 KZ650
                        78 KZ750

                        Comment

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