5th gen 'clunk' at idle, not moving

Discussion in 'Mechanics Garage' started by crewwolfy, May 16, 2021.

  1. crewwolfy

    crewwolfy New Member

    Country:
    United States
    Joined:
    Mar 31, 2010
    Messages:
    36
    Likes Received:
    0
    Trophy Points:
    6
    Location:
    Chicago, IL
    Map
    Hi all,

    I just performed a valve clearance check and replaced some shims. After buttoning everything back up, I'm running into a concerning 'clunk' sound at random moments:



    I don't hear this while the 'choke' is engaged and the bike is warming up. Generally the bike will idle without that valve at ~150 degrees. That's the temperature the bike's at in the video, no choke. I haven't taken it off the center stand, so no road experience. The sound appears randomly and of varying intensity, at ~19 seconds and ~28 seconds in the video.

    I did button everything up once already, but heard a very faint tapping noise once riding (not the current issue). Went back home, disassembled, and one of the camshafts was a tooth off alignment. I've followed instructions and torqued all bolts per the service manual. The only other change: the flapper valve was removed be PO, but the junction was never plugged, so I attached a plugged tube to the correct joint.

    I assume I'll be taking it apart and checking the camshaft alignment once again, but hoping someone has a good idea of what may be happening. Thanks!

    (The bike lived a rough life before me, but I've put ~45k well-maintained miles on it -currently at 66k- with no engine troubles over the past 10 years.)
     
  2. Diving Pete

    Diving Pete Member

    Country:
    United Kingdom
    Joined:
    Mar 25, 2016
    Messages:
    1,969
    Likes Received:
    548
    Trophy Points:
    143
    Location:
    London
    Map
    Something doesn't sound normal to me.. I think its coming apart again.
     
  3. crewwolfy

    crewwolfy New Member

    Country:
    United States
    Joined:
    Mar 31, 2010
    Messages:
    36
    Likes Received:
    0
    Trophy Points:
    6
    Location:
    Chicago, IL
    Map
    I'd like to dislike this comment, but you're right. I've dug back in and have the rear valve cover off, and it looks like the exhaust cam is off by one tooth again.. More diligence on multiple engine rotations before rechecking new adjustments this time.. I'm sure there's risk of destroyed valves, but likelihood?
     
  4. Grum

    Grum New Member

    Country:
    Australia
    Joined:
    Dec 14, 2020
    Messages:
    304
    Likes Received:
    110
    Trophy Points:
    43
    Does the sound change if you pull the clutch lever in?
     
  5. crewwolfy

    crewwolfy New Member

    Country:
    United States
    Joined:
    Mar 31, 2010
    Messages:
    36
    Likes Received:
    0
    Trophy Points:
    6
    Location:
    Chicago, IL
    Map
    I never tried that. The bike was always in neutral at the time, but that would have been a good action to check. Both valve covers are already off (front intake was also off by a tooth), so I can't test that at this time.
     
  6. raYzerman

    raYzerman Member

    Country:
    Canada
    Joined:
    Dec 3, 2019
    Messages:
    1,228
    Likes Received:
    450
    Trophy Points:
    113
    Location:
    Millgrove, ON
    Map
    One tooth off shouldn't destroy valves, and it wouldn't run that smooth. Get your cam timing corrected and try again.....
     
    Derek A Sinclair likes this.
  7. crewwolfy

    crewwolfy New Member

    Country:
    United States
    Joined:
    Mar 31, 2010
    Messages:
    36
    Likes Received:
    0
    Trophy Points:
    6
    Location:
    Chicago, IL
    Map
    Thanks all. Apologies for the radio silence, just moved (same building/garage). I decided to change the valve cover gaskets while I was in there, which is proving troublesome.. Rear on, front to come..
     
  8. Derek A Sinclair

    Derek A Sinclair New Member

    Country:
    United States
    Joined:
    Apr 2, 2021
    Messages:
    16
    Likes Received:
    3
    Trophy Points:
    3
    The "clunk" is a misfire because the timing is off by a few degrees. You have a cam misaligned. If it's just one tooth, youre probably ok as far as valve/piston damage is concerned. The fact that it took 2 tries to start was also a clue. I could tell as soon as it started that the timing was off. A Honda V4 should sound much smoother than that. Get your timing set right and you'll be good.
     
Related Topics

Share This Page