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'77 GS750 engine noise

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    #1

    '77 GS750 engine noise

    Hey all, I've slowly been working on bringing an old GS back to life and have a new engine noise that has developed. Not sure if it's related, but I performed a vacuum sync yesterday, went for a short test ride last night and started hearing this noise - I'm pretty sure I've heard it before, but it's much more prevalent now after the vacuum sync. It sounds like maybe it's cam walk, but it seems to be too consistent compared to videos I've seen of that condition. Valve clearances are in spec. That was one of the first things I did years ago.

    In the vid below there's a rhythmic knocking noise that I'm concerned about, and hoping someone has some insight. Thanks in advance!
    Last edited by billyhoyle; 09-08-2021, 02:45 PM.
    1977 GS750
    Tags: None
    #2
    Well I think it might just be a terrible exhaust leak that makes it sound super noisy. I installed this used exhaust from eBay (it's a Mac 4-1 which isn't great, but better than the straight pipes it had previously) the other day and didn't thoroughly check for leaks. I just torqued it down a little more and the noise is reduced (but there is still a leak or 4). I'm waiting on new gaskets in the mail and will re-evaluate at that point.
    1977 GS750

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      #3
      A leaky exhaust at the head can sound like mechanical mayhem.
      Preys on your mind as you ride along, thinking there's something going really wrong.
      ---- Dave

      Only a dog knows why a motorcyclist sticks his head out of a car window

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        #4
        Originally posted by billyhoyle View Post
        Well I think it might just be a terrible exhaust leak that makes it sound super noisy. I installed this used exhaust from eBay (it's a Mac 4-1 which isn't great, but better than the straight pipes it had previously) the other day and didn't thoroughly check for leaks. I just torqued it down a little more and the noise is reduced (but there is still a leak or 4). I'm waiting on new gaskets in the mail and will re-evaluate at that point.
        Did it end up being noise from an exhaust leak? I have a similar noise that seems to be on the right side of the bike. Felt around to see if I could feel any exhaust leaking from the gaskets but it seems fine. May replace them anyway.
        1982 GS1100gl

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          #5
          New gaskets helped a LOT. There's still a bit of the noise I was hearing, but I don't think it's anything to worry about.
          1977 GS750

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            #6
            Could be excessive valve clearances, cam chain tension, loose parts rattling. Ive chased noises down to being loose rear brake tie bars, side stand, motor mount bolts and muffler brackets before.

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              #7
              Sounds too loud to be 'cam walk,' right? A little concerning, though.
              1982 GS1100E V&H "SS" exhaust, APE pods, 1150 oil cooler, 140 speedo, 99.3 rear wheel HP, black engine, '83 red

              2016 XL883L sigpic Two-tone blue and white. Almost 42 hp! Status: destroyed, now owned by the insurance company. The hole in my memory starts an hour before the accident and ends 24 hours after.

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