1. Some members were not receiving emails sent from XJbikes.com. For example: "Forgot your password?" function to reset your password would not send email to some members. I believe this has been resolved now. Please use "Contact Us" form (see page footer link) if you still have email issues. SnoSheriff

    Hello Guest. You have limited privileges and you can't "SEARCH" the forums. Please "Log In" or "Sign Up" for additional functionality. Click HERE to proceed.

header pipes?

Discussion in 'XJ Technical Chat' started by carbineken, Jul 11, 2011.

  1. carbineken

    carbineken Member

    Messages:
    104
    Likes Received:
    0
    Trophy Points:
    16
    Location:
    Wagoner, OK
    Do XJ's have double walled head pipes? I've got an awful rattle/buzzing sound coming from the front that I cannot track down. It happens from about 4800-5100 rpm. It's like a switch being flipped.....4800=BUZZZZZZZ....5150=sewing machine. And vibrates through the whole bike.
    An inner wall coming loose on one of the head pipes is the only thing I can think of.
     
  2. waldo

    waldo Member

    Messages:
    871
    Likes Received:
    1
    Trophy Points:
    18
    Location:
    San Jose, Ca. 95125
    Yes they do if you tap the pipe you probably will be able to tell which ones are bad
     
  3. day7a1

    day7a1 Member

    Messages:
    623
    Likes Received:
    6
    Trophy Points:
    18
    Location:
    San Diego, CA
    Yes they do...but that's not your problem.

    the 650j's are known to buzz at that rpm...you can minimize it by ensuring you have the fin vibration dampeners (little rubber pieces in the fins on each side of the motor), good rubber in the mounts, properly synced and valves adjusted.

    I'm willing to bet you are missing the dampeners...mine started to do it much more when I accidentally threw mine away :(
     
  4. carbineken

    carbineken Member

    Messages:
    104
    Likes Received:
    0
    Trophy Points:
    16
    Location:
    Wagoner, OK
    Never even thought of that. I'll take a look for those dampers and check my donor bike for replacements.

    I was thinking head pipes because I had an issue with #2 breaking its studs off. I drilled and heli-coiled them and it seemed like the noise started shortly after that. At any rate I'll check the dampers.

    I've tried tapping the head pipes and couldn't tell anything from it.
     
  5. bigfitz52

    bigfitz52 Well-Known Member Premium Member

    Messages:
    21,283
    Likes Received:
    419
    Trophy Points:
    83
    Location:
    Rural SE Michigan 60 miles N of Motown
    I can tell you this much, for sure: Once an inner pipe does start crackiing/breaking up, you'll start to see bluing on the outer pipe as a result of the hot gasses hitting it from inside.

    As for your rattle; day7a1 is right about 5000 RPM being the primary "buzz frequency" so anything that's loose is going to rattle and buzz at right around those RPMs.

    Other possibilities (stuff that's happened to me anyway) one or more head pipes loose at their lower clamp; or a broken rubber relay mount allowing a relay to rest against something and "sing" at certain RPM. Or for that matter, anything that's loose enough to rattle at the right harmonic frequency. I've had a small "harmonic buzz" driving me batty lately; turns out it's the plastic snap-clip on my tankbag's retaining strap "singing" against the front edge of the gas tank when it happens to end up close enough.
     
  6. carbineken

    carbineken Member

    Messages:
    104
    Likes Received:
    0
    Trophy Points:
    16
    Location:
    Wagoner, OK
    As near as I can tell all the dampers are there. None of the pipes are turning blue. I've checked the lower clamps several times they are tight..that doesn't necessarily mean the pipes are tight inside them though. So I'll give that a look too. I may pull the gas tank off this weekend and run the engine up to 5000 and see if its anything under there. Got a busted Sporty I'm trying to work on and the wife is hounding me about her XJ hard to spend much time on the only running bike.
     
  7. ken007

    ken007 Member

    Messages:
    477
    Likes Received:
    2
    Trophy Points:
    18
    Location:
    Brisbane, Australia
    gday, my bike runs very well, everything where it should be, at around 5000RPM mine gets a buzz in it but disappears soon after. it bugs the hell out of me cause on our highways the speed limits 100K/PH,exactly were it buzzes,so i go 95 or a 105,smooth as silk,but it still bugs me.
     

Share This Page