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KZ400 Top End Noise

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    KZ400 Top End Noise

    Not sure if anyone has any experience with these but I rescued a 79" kZ400 for $80 bucks and got the freshly rebuilt carbs and my homemade airbox/carb boots on it today and fired it up. Starts right off, runs nicely but it has what sounds like a top end noise and by noise I mean almost a knocking sound. Does not seem to effect the way it runs. Have very limited experience with KZ's but my son had one a couple years ago and never heard anything like this. Anything thoughts right off the top? Too loud to be cam chain, I was thinking maybe a broken valve spring but would that not be effecting performance? Any help is appreciated guys

    #2
    bump

    no suggestions?

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      #3
      Make a video of the noise.
      De-stinking Penelope http://thegsresources.com/_forum/sho...d.php?t=179245

      http://www.thegsresources.com/_forum...35#post1625535

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        #4
        Pretty familiar with that series, however nothing specific to contribute, only thing I might suggest is pinpointing the location of the noise with an automotive stethoscope, or homemade similar. Is it a 'loud' tapping or deeper toned 'knocking'. My (long ago) past experience with those models had a great deal more to do with a horrendous history of top-end oil leakage, but the '79-on version ironed that problem out. Dales' suggestion of recording the sound is a good one.
        sigpicSome of the totally committed probably should be.
        '58 + '63 Vespa 150's' (London, GB/RI, US)
        '67 X6 T20 ('67 Long Beach, Ca.- misty-eyed)
        '71 Kaw. A1-ugh ('71 SF, CA- worked @ Kaw dlr)
        '66 Yam. YL1('72 SF-commuter beater)
        '73 Kaw. S2A-2Xugh ('73 SF-still parts slave)
        '78 GS 750C ('77 SF-old faithful-killed by son)
        '81 KZ 750E ('81 SF-back to Kaw. dlr)
        '81 GS 650G ('08 back to NE&ME- (project)
        '82 GS '82 (2) GS650GZ, L, Middlebury, G current

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          #5
          Decided to pull the valve caps off and have a look (this has the adjustable valves) and sure enough one of them was missing it's nut. It was just loose inside there, surprised it ran as well as it did! Pulled the valve cover off and sure enough found the missing nut. Adjusted the valves and mystery noise is gone!

          Comment


            #6
            Fantastic! Always great when things work out that way!
            sigpicSome of the totally committed probably should be.
            '58 + '63 Vespa 150's' (London, GB/RI, US)
            '67 X6 T20 ('67 Long Beach, Ca.- misty-eyed)
            '71 Kaw. A1-ugh ('71 SF, CA- worked @ Kaw dlr)
            '66 Yam. YL1('72 SF-commuter beater)
            '73 Kaw. S2A-2Xugh ('73 SF-still parts slave)
            '78 GS 750C ('77 SF-old faithful-killed by son)
            '81 KZ 750E ('81 SF-back to Kaw. dlr)
            '81 GS 650G ('08 back to NE&ME- (project)
            '82 GS '82 (2) GS650GZ, L, Middlebury, G current

            Comment


              #7
              Originally posted by nejeff View Post
              Decided to pull the valve caps off and have a look (this has the adjustable valves) and sure enough one of them was missing it's nut. It was just loose inside there, surprised it ran as well as it did! Pulled the valve cover off and sure enough found the missing nut. Adjusted the valves and mystery noise is gone!
              What luck! That nut could have caused some trouble in there.

              Comment


                #8
                Originally posted by winfield View Post
                What luck! That nut could have caused some trouble in there.
                I was just glad I found it in there! I got to say a 5 minute valve adjustment is pretty nice!

                Comment

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