Announcement

Collapse
No announcement yet.

knocking noise at RPM above 3000.

Collapse
X
Collapse
 
  • Page of 3
  • Filter
  • Time
  • Show
Clear All
new posts
Previous 1 2 3 template Next
  • #1

    knocking noise at RPM above 3000.

    Hi all.
    My 81 Special has had a fairly loud knocking noise above 3K RPM for some time. It also seems to be affected by engine load. If I'm cruising at say 60 mph in 4th it is loudest but if I accelerate or climb a hill it seems to go away. If I actually knew anything about this engine, I would say it sounded like either a connecting rod big or small end or maybe a crank bearing. the nature of the noise doesn't really sound like the cams or rockers but I suppose that could be it. I did have one mechanic say he thought it was the vacuum advance mechanism. The thing runs great and has no unusual vibration or oil usage or leaks. Any suggestions are welcomed.
    Thanks.
    81 MNS
    Tags: None
  • #2
    Vacuum advance hose plugs onto top frontside of #2 carb.
    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
      Advance

      Not enough info to really diagnos yet. When did it start? Suddenly or has it developed and worsened over time. With what we know to date. The advance seems a likely culprit and motoman has given you the most common cause. Ensure the small vac hose is not connected to the intake boot but rather the #2 carb.
      mack
      79 XS 1100 SF Special
      HERMES
      original owner
      http://i946.photobucket.com/albums/a...ps6932d5df.jpg

      81 XS 1100 LH MNS
      SPICA
      http://i946.photobucket.com/albums/ad305/mack-055/2.jpg

      78 XS 11E
      IOTA
      https://youtu.be/wB5Jfbp6SUc
      https://youtu.be/RaI3WYHSuWA



      Have recovery trailer and shop if you breakdown in my area.
      Frankford, Ont, Canada
      613-398-6186

      Comment

      • #4
        Read this TSB on the Vacuum advance.......

        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

        • #5
          Has the bike always had this noise? Have the carbs been off recently and vacuum advance hose is on the wrong place like Motoman said a few posts ago?
          Howard

          ZRX1200

          BTW, ZRX carbs have the same spacing as the XS11... http://www.xs11.com/forum/showthread.php?t=35462

          Comment

          • #6
            Knock Knock

            Hi tqs335, and welcome to the forum.

            I have 2 xs1100LG's (MNS)
            One has the same knocking around 3 to 4k rpm.
            The other one doesn't!

            Disconnecting the vac advance seems to minimize the knocking but also
            seems to have a negative affect on overall performance.

            This problem has caused me to start knocking my head against the wall!
            and that didn't help either!

            Good luck tqs335..
            Please let me know if you find a resolution...
            I'll be watching this thread closely!
            Bob's Bikes:
            79SF, Military theme bike

            Bob's websites:
            https://projectxs11.wordpress.com
            https://rucksackgrunt.com

            Bob's Books:
            "            Project XS11"
            "Rucksack Grunt"
            "Jean's Heroic Journey"


            Bob's Parts:
            For Sale Here.

            Comment

            • #7
              Originally posted by Ranger_xs1100 View Post
              Hi tqs335, and welcome to the forum.

              I have 2 xs1100LG's (MNS)
              One has the same knocking around 3 to 4k rpm.
              The other one doesn't!

              Disconnecting the vac advance seems to minimize the knocking but also
              seems to have a negative affect on overall performance.

              This problem has caused me to start knocking my head against the wall!
              and that didn't help either!

              Good luck tqs335..
              Please let me know if you find a resolution...
              I'll be watching this thread closely!
              If you read the TSB I posted the fix back in the day was a modified vacuum pod. A part that is no longer available. Some were fixed and some weren't that explains why you have one that does, and one that doesn't. Try swapping the vacuum pods and see if the problem moves from one bike to the other.

              Also, in the TSB it says that the detonation is NOT damaging to the engine.
              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

              • #8
                Knock Knock

                I replaced that vacuum pod/canister/plunger unit (whatever it is called) with one from a 79 standard, which I believe used the same part number that the tech service bulletin recommends. There seemed to be some improvement but not an elimination of the knocking. I haven't swapped the one between my 2 LG's which will be my next step but it will have to wait til warmer springtime weather now.
                Thanks BA80.
                Bob's Bikes:
                79SF, Military theme bike

                Bob's websites:
                https://projectxs11.wordpress.com
                https://rucksackgrunt.com

                Bob's Books:
                "                Project XS11"
                "Rucksack Grunt"
                "Jean's Heroic Journey"


                Bob's Parts:
                For Sale Here.

                Comment

                • #9
                  Thanks gentlemen!

                  Thank all of you who generously responded to my post.
                  Im going to dive into the problem based on your advise and information. I really hope to make some progress on this. I love riding my bike but the noise gets a little annoying sometimes.
                  Thanks again!
                  81 MNS

                  Comment

                  • #10
                    Ba80

                    You have any other service bullets? Are they available on this site?
                    mack
                    79 XS 1100 SF Special
                    HERMES
                    original owner
                    http://i946.photobucket.com/albums/a...ps6932d5df.jpg

                    81 XS 1100 LH MNS
                    SPICA
                    http://i946.photobucket.com/albums/ad305/mack-055/2.jpg

                    78 XS 11E
                    IOTA
                    https://youtu.be/wB5Jfbp6SUc
                    https://youtu.be/RaI3WYHSuWA



                    Have recovery trailer and shop if you breakdown in my area.
                    Frankford, Ont, Canada
                    613-398-6186

                    Comment

                    • #11
                      No, sorry Mack. I have that one saved from several years ago when I still had the original 3J6 engine. I had the same knock at highway speed.

                      I believe that one came from TC.
                      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

                      • #12
                        Fuel

                        Have you tried different octane fuels? JAT
                        1981 XS1100H Venturer
                        K&N Air Filter
                        ACCT
                        Custom Paint by Deitz
                        Geezer Rectifier/Regulator
                        Chacal Stainless Steel Braided Brake Lines
                        Chrome Front Rotor & Caliper Covers
                        Stebel Nautilus Horn
                        EBC Front Rotors
                        Limie Accent Moves On In 2015

                        Mike

                        Comment

                        • #13
                          Originally posted by mack View Post
                          You have any other service bullets? Are they available on this site?
                          Hey Mack,

                          IIRC, I did post that one a while/years ago back when Yamaha had the TSB's on their Parts Fiche site, but since they revamped the site, they only show the parts lists, and so the TSB's aren't there anymore, and I didn't think to try to access and download ALL of them!?

                          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

                          • #14
                            Tc

                            Yes when they revamped we lost fost of the models. However I found this site: It is very close to the fische but no FSB's:
                            http://store.speedandsportinc.com/
                            mack
                            79 XS 1100 SF Special
                            HERMES
                            original owner
                            http://i946.photobucket.com/albums/a...ps6932d5df.jpg

                            81 XS 1100 LH MNS
                            SPICA
                            http://i946.photobucket.com/albums/ad305/mack-055/2.jpg

                            78 XS 11E
                            IOTA
                            https://youtu.be/wB5Jfbp6SUc
                            https://youtu.be/RaI3WYHSuWA



                            Have recovery trailer and shop if you breakdown in my area.
                            Frankford, Ont, Canada
                            613-398-6186

                            Comment

                            • #15
                              Originally posted by BA80 View Post
                              No, sorry Mack. I have that one saved from several years ago when I still had the original 3J6 engine. I had the same knock at highway speed.

                              I believe that one came from TC.
                              Vacuum can has to match year motor and initial static timing assembly. They go hand in hand.
                              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

                              Previous 1 2 3 template Next
                              Working...
                              X