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Thread: Clanking sound on start-up

  1. #1
    R1100R "Traveler" DesertRider's Avatar
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    Clanking sound on start-up

    I have a '96 R1100R that makes a curious clanking sound on start-up, particularly when on the choke. It starts with no problem, but when cold and idling, particularly idling on the choke, I hear an irregular clanking which seems to come from the front of the engine. Here's a recording of it:

    Recording of engine idling and clanking

    In this sound sequence the engine is not quite full cold (I'd started and run it a minute or two a couple of times earlier in the morning), but not fully warmed up. The sequence starts with the engine idling with the choke off, then about 5 seconds into it the choke goes on (you can hear the engine RPM go up), there's the intermittent clanking sound, there's about 25 seconds of that, then I turned off the choke, the idle goes back to normal.

    When the engine is fully cold the clanking will sometimes occur with the choke off as well, and once warmed up it doesn't do it at all. The engine seems to run fine otherwise other than occasional surging at steady throttle openings.

    Any suggestions on what this might be? This is my first Boxer, so not sure if this kind of clanking is normal start-up noise or something wrong. I've pulled off the pulley cover to see if it might be something under there, everything looks OK.

    Ideas? Thoughts? Suggestions?

    Any help anyone can provide would be most appreciated -- thanks.

    ---

    History of the bike: It was purchased in '96, ridden for less than 2000 miles, then put into storage until mid-2003, at which point a dealer serviced it and said they did all the right things to bring it out of storage (oil change, brake fluid change, check for leaks, etc.). An elderly gentleman then bought it, rode it for a couple of months, decided it was too big a bike for him, traded it back in. I bought it in December '03, and other than changing the tires (tires were original -- unworn but almost 9 years old), I haven't done much to it but add some accessories and put about 1000 miles on it.

    For those with super-sensitive ears (and a fast connection), here's a link to the full-fidelity recording (1.5 Mb):

    Full-fidelity recording
    DesertRider in sunny Arizona, USA


  2. #2
    Focused kbasa's Avatar
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    Does this sound go away after the bike warms up? Does it go away if you pull the clutch in?

    It's really hard to tell from here, but I'm wondering if it's the usual oilhead transmission noise or if you have a cam chain tensioner that's not tensioning like it's supposed to.
    Dave Swider
    Marin County, CA

    Some bikes. Some with motors, some without.

  3. #3
    R1100R "Traveler" DesertRider's Avatar
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    Originally posted by KBasa
    Does this sound go away after the bike warms up? Does it go away if you pull the clutch in?
    Checked it this morning when it was full cold. Pulling in the clutch makes no difference. It does go away when the bike is warmed up. Could be the cam chain tensioner? Any other possibilities to check?

    If it's the cam chain tensioner, why would it go away once it's warmed up?

    Thanks,
    DesertRider in sunny Arizona, USA


  4. #4
    Focused kbasa's Avatar
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    The cam chain tensioner works on oil pressure kind of like an hydraulic valve lifter in a Chevy V8. If the tensioner has a partly blocked orifice, it'll take a while to finally get pumped up full to maintain proper chain tension.
    Dave Swider
    Marin County, CA

    Some bikes. Some with motors, some without.

  5. #5
    Registered User chickenman_26's Avatar
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    You have a loose valve. Adjust 'em.

  6. #6
    Alps Adventurer GlobalRider's Avatar
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    Originally posted by KBasa
    The cam chain tensioner works on oil pressure...
    And that is what that chatter is that we all hear for the first second after start-up.

  7. #7
    Alps Adventurer GlobalRider's Avatar
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    Originally posted by DesertRider
    Could be the cam chain tensioner? Any other possibilities to check?

    If it's the cam chain tensioner, why would it go away once it's warmed up?
    If it were the valves, you would hear a tick at all rpms. But you can check them.

    I think it is your cam chain tensioner. It goes away because warm thin oil can pump up the cam chain tensioner piston - I'm assuming that is how they work. The ticking you hear varies with rpm because the chain flops differently when loose at various rpms. Ever look at a loose drive chain. Change the speed and its like you are looking at variable standing waves.

    Even when the oil is cold, does the ticking go away if you take the revs up to 2500 rpm?

    I'm new to these oilheads so maybe someone else can help you out with removing the tensioner, testing for sticking, etc. Are these accessible without stripping the engine?

  8. #8
    Registered User chickenman_26's Avatar
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    Originally posted by Global Rider

    I'm new to these oilheads so maybe someone else can help you out with removing the tensioner, testing for sticking, etc. Are these accessible without stripping the engine?
    Yes, they are, but the left and right are different. Don't mix 'em up.

    Stu

  9. #9
    R1100R "Traveler" DesertRider's Avatar
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    It really doesn't sound like a valve. Loose valves make a ticking or tapping sound and it's very regular. This is irregular and definitely a "clank." You can hear it fairly clearly in the audio file I posted. Just in case I'll do a check of valve clearances, but I really don't think that'
    s it.

    Loose cam chain tensioner could be it, i.e., the sound could be cam chain slapping on something. But I've never done anything with cam chain tensioners, will have to look up in the manual what to do about them (any thoughts welcome).
    DesertRider in sunny Arizona, USA


  10. #10
    Registered User chickenman_26's Avatar
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    Your recording was good, but still, it's really hard to diagnose noises without hearing them in person. What part of sunny AZ do you live in? I'm in North Scottsdale, and the coffee pot is always on.

    Stu

  11. #11
    Riding for the SON
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    When the knocking is going on, put your hand under and to the back side of the throttle body and feel the wheel the throttle cabe hooks to. If it is moving and your finger stoppes the sound, you have found the sorce of the clanking. It won't cause any problems, but some fine adjustment may make it go away. God bless.

  12. #12
    R1100R "Traveler" DesertRider's Avatar
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    Originally posted by Roy Barnes
    When the knocking is going on, put your hand under and to the back side of the throttle body and feel the wheel the throttle cabe hooks to. If it is moving and your finger stoppes the sound, you have found the sorce of the clanking. ...
    Great suggestion -- I'll give that a shot. Thanks!
    DesertRider in sunny Arizona, USA


  13. #13
    R1100R "Traveler" DesertRider's Avatar
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    Originally posted by Chickenman_26
    Your recording was good, but still, it's really hard to diagnose noises without hearing them in person. What part of sunny AZ do you live in? I'm in North Scottsdale, and the coffee pot is always on. Stu
    Stu, that's an offer that's hard to pass up, clanking sound or not. Drop me a line (wm-at-thedesertrider.com) and let's get together. I'm in northeast Phoenix.
    DesertRider in sunny Arizona, USA


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