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Thread: '82 GS450 Engine Chatter - Cam Related?

  1. #1
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    Default '82 GS450 Engine Chatter - Cam Related?

    Hi everyone, my GS450 was running very well (I guess it still kinda does, fires right up and will run and rev while making this chatter) and then it started a very loud and tactile ticking when running. Definitely sounds like it is coming from the head/cams and it causes the cam chain tensioner to go crazy. When it first began, wiggling the tach cable stopped the chatter to allow for an afternoon ride. Then I had it start in the middle of a ride where I had to pull over and wiggle the cable before continuing. Now no amount of wiggling allows the bike to run normally.

    I first suspected maybe the tach gear was binding but it checked out fine. I pulled the valve cover off and didn't see anything obviously wrong. Though in hindsight I should've manually turned the crank while the cover was off, might've been able to feel something. A guy on the Facebook group suggested re-torquing the camshaft clamp bolts, unfortunately that didn't make a difference. I also removed and reset the tensioner. Curious if anyone has an idea on where to go from here.

    I have two videos from when wiggling the tach cable made a difference. The first is of the chatter on a cold start. The second shows wiggling the tach cable and the bike starting and sounding normally.

    https://drive.google.com/file/d/1r_P...ew?usp=sharing

    https://drive.google.com/file/d/1gMw...ew?usp=sharing

    I appreciate any help and input!
    1982 Suzuki GS450TXZ
    1985 Honda CB700SC Nighthawk S

  2. #2
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    Form the described symptoms, it's almost sure that the tach gear (both on cam and the gear itself), tach cable or combination thereof must be the culprit.

    Remove valve cover, inspect thoroughly, take pictures and put them into this thread.

    Also note that any of the parts number 19 to 22 on the respective parts fiche are suspect (hotlinking picture from https://www.cmsnl.com/suzuki-gs450e-...list/FIG3.html, not sure if it works):
    Last edited by roeme; 02-23-2021 at 06:21 AM.
    #1: 1979 GS 550 EC "Red" Very first Bike / Overhaul thread        New here? ☛ Read the Top 10 Newbie mistakes thread
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  3. #3
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    Something with the tach gear makes sense but when I disassembled it nothing looked scored or gave an indication of something being off. It came apart no problem (once I pried loose #20 on the fiche from the head, that was pretty stubborn) and everything fit back together without a fight. I should mention that I did replace the oil seal while looking at it. I didn't get pictures of everything while it was apart, but here is the gear removed.



    I probably should've waited another week or so to post this thread, won't have time to take the valve cover off until maybe next weekend. Thanks for the thoughts, I'll update this thread with some pictures of the cover removed when I have a chance.
    1982 Suzuki GS450TXZ
    1985 Honda CB700SC Nighthawk S

  4. #4
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    The cam gear is softer than the driven gear. If you try to install the exhaust cam with the tach drive installed, the cam gear can get munched if it doesn't mesh right. Make sure the engine gets turned two revolutions and examine the full cam gear as it goes by.

    If this is the problem then you don't have any options but to replace the cam. I know it happens because I've been a victim of my own carelessness in this regard. If the problem was the cable itself I'd think it would be broken by now.
    '82 GS450T

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    Quote Originally Posted by John Park View Post
    (...)

    If this is the problem then you don't have any options but to replace the cam. (...)
    Well, one option would be to temporarily forego RPM indication and plug the hole.
    #1: 1979 GS 550 EC "Red" Very first Bike / Overhaul thread        New here? ☛ Read the Top 10 Newbie mistakes thread
    #2: 1978 GS 550 EC "Blue" Can't make it a donor / "Rebuild" thread     Manuals (and much more): See Cliff's homepage here
    #3: 2014 Moto Guzzi V7 II Racer One needs a runner while wrenching

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    Gorminrider is offline Forum Sage Past Site Supporter
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    haha! ^^Yes. Tachometers aren't awfully useful anyways unless perhaps you're deaf. Speedos-you need. Tachs you don't.

    But that gear looks ok. What I don't get is your timing chain "going crazy"..
    and then it started a very loud and tactile ticking when running. Definitely sounds like it is coming from the head/cams and it causes the cam chain tensioner to go crazy.
    I don't see an indication that your tach caused it and I am seriously wondering where the tensioner is "at" after viewing the 1st video. It is NOT supposed to do that.

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    Quote Originally Posted by Gorminrider View Post
    haha! ^^Yes. Tachometers aren't awfully useful anyways unless perhaps you're deaf. Speedos-you need. Tachs you don't.

    But that gear looks ok. What I don't get is your timing chain "going crazy".. I don't see an indication that your tach caused it and I am seriously wondering where the tensioner is "at" after viewing the 1st video. It is NOT supposed to do that.
    Hmmm, you think by wiggling the cable he artificially tensioned the timing chain, and then the whole system went into just the right resonance equilibrium? Or that was just the right amount of resistance to whack the tensioner back into proper operation?

    Hmmm. I'd first try to conclusively rule out the tach gear. Note that the tach gear picture is from _before_ he put the engine back together.
    #1: 1979 GS 550 EC "Red" Very first Bike / Overhaul thread        New here? ☛ Read the Top 10 Newbie mistakes thread
    #2: 1978 GS 550 EC "Blue" Can't make it a donor / "Rebuild" thread     Manuals (and much more): See Cliff's homepage here
    #3: 2014 Moto Guzzi V7 II Racer One needs a runner while wrenching

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    Quote Originally Posted by roeme View Post
    Hmmm, you think by wiggling the cable he artificially tensioned the timing chain, and then the whole system went into just the right resonance equilibrium? Or that was just the right amount of resistance to whack the tensioner back into proper operation?
    It sounds crazy, but I think you might just have something there.

    ---- Dave
    79 GS850N - Might be a trike soon.
    80 GS850T Single HIF38 S.U. SH775, Tow bar, Pantera II. Gnarly workhorse & daily driver.
    79 XS650SE - Pragmatic Ratter - goes better than a manky old twin should.
    92 XJ900F - Fairly Stock, for now.

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

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    Gorminrider is offline Forum Sage Past Site Supporter
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    Quote Originally Posted by roeme View Post
    Hmmm, you think by wiggling the cable he artificially tensioned the timing chain, and then the whole system went into just the right resonance equilibrium? Or that was just the right amount of resistance to whack the tensioner back into proper operation?

    Hmmm. I'd first try to conclusively rule out the tach gear. Note that the tach gear picture is from _before_ he put the engine back together.
    Did you see the video?

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    Quote Originally Posted by Gorminrider View Post
    Did you see the video?
    Yes, what about it? It's exactly why I'm a bit stumped that by merely wiggling the tach cable the issue (apparently) went away.

    But also, this could've been sheer coincidence, forgot to take this into account.
    #1: 1979 GS 550 EC "Red" Very first Bike / Overhaul thread        New here? ☛ Read the Top 10 Newbie mistakes thread
    #2: 1978 GS 550 EC "Blue" Can't make it a donor / "Rebuild" thread     Manuals (and much more): See Cliff's homepage here
    #3: 2014 Moto Guzzi V7 II Racer One needs a runner while wrenching

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