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Thread: piston rings

  1. #61
    Senior Member Cooter's Avatar
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    Putting it on a dyno could at least tell you if it's running well and clean. If it is, then this is all in your head. If it is not, then they will have a clue as to what could be wrong. Rich, lean, missing, etc.

  2. #62
    Senior Member Barrett's Avatar
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    Typical causes of excessive engine vibration in the XB-XL-XR rubber mounted engine platform are the following:
    1-One or more mounting points in the engine-to-frame configuration either cracked...incorrectly assembled...bent.
    2-On an XB platform...one or more of the 4 mounting points for the complete stock exhaust system is missing or cracked or incorrectly installed allowing excess shaking between the headers/muffler/engine assembly. The 4 attachment points are the 2 header tubes to exhaust ports and the 2 half-moon shaped muffler brackets to engine case tabs.
    3-Failing crank-pin assembly that may or may not emit a light squeaking noise upon start-up and shut-down. A crank-pin assembly that has been subjected to violent jarring from an accident...been left running on its side after an accident...or subjected to ham-fisted wrenching by someone using an impact wrench on the front sprocket/compensator nut...will most often cause the 2 crankshaft flywheels to eventually run out of phase and misalign themselves. End result is horrible primary imbalance causing excess vibration that can't be resolved.
    NO amount of "tuning" will resolve any of the above issues. From your accident description, associated pics, and difficulties remounting the drive-line into the tank/frame....IMO this thing should have never been put back on the road.

  3. #63
    Senior Member Cooter's Avatar
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    Oh man, I didn't even think of the crank being out of phase. That could do it for sure

    Dang HD and their stick and rock 'technology', lol.

  4. #64
    Quote Originally Posted by Barrett View Post
    Typical causes of excessive engine vibration in the XB-XL-XR rubber mounted engine platform are the following:
    1-One or more mounting points in the engine-to-frame configuration either cracked...incorrectly assembled...bent.
    2-On an XB platform...one or more of the 4 mounting points for the complete stock exhaust system is missing or cracked or incorrectly installed allowing excess shaking between the headers/muffler/engine assembly. The 4 attachment points are the 2 header tubes to exhaust ports and the 2 half-moon shaped muffler brackets to engine case tabs.
    3-Failing crank-pin assembly that may or may not emit a light squeaking noise upon start-up and shut-down. A crank-pin assembly that has been subjected to violent jarring from an accident...been left running on its side after an accident...or subjected to ham-fisted wrenching by someone using an impact wrench on the front sprocket/compensator nut...will most often cause the 2 crankshaft flywheels to eventually run out of phase and misalign themselves. End result is horrible primary imbalance causing excess vibration that can't be resolved.
    NO amount of "tuning" will resolve any of the above issues. From your accident description, associated pics, and difficulties remounting the drive-line into the tank/frame....IMO this thing should have never been put back on the road.
    Hmmm. I'll try to reiterate.

    All the mounts (front back, and lateral) look good. I installed a new front isolator with the thought that maybe the old one was getting hard. No dice.

    The exhaust was removed and re installed according to SM specs, all the pieces are there and tight and no cracks detected, so I would be open to what I could do there.

    If it is a crank issue, it would be a pure coincidence that it showed up after I happened to button the thing up.?? How would I check that? I did adjust the primary chain tension, but it was not way out of wack.

    No, I did not have any real difficulties remounting the motor into the frame. I mentioned one of the lateral tie lines was not quite lining up. Where I had the issue was getting the back cylinder piston and rings into the jug.

    As to the comment 'this should never have been put back on the road' I'll leave for another time. Other than the vibration, the bike is in perfect operating condition and underwent a thorough state safety inspection. Lots of new parts and time involved fixing this thing up.

    Cooter, I'll have to see where the nearest dyno is. I'm in the middle of nowhere. And I would politely say, no it's not in my head.

    The only code that it is throwing is that the muffler valve is stuck shut.

    Look, I'm not an ace mechanic by any stretch, (which is why I'm on here in the first place) but I am fairly mechanically inclined and can follow directions fairly well. All I am trying to do is exhaust my options of things I can do and try before I knuckle under and take it to a very expensive Harley dealership.

    Thanks everyone for your input.

  5. #65
    Senior Member 34nineteen's Avatar
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    Quote Originally Posted by Barrett View Post



    3-Failing crank-pin assembly that may or may not emit a light squeaking noise upon start-up and shut-down. A crank-pin assembly that has been subjected to violent jarring from an accident...been left running on its side after an accident...or subjected to ham-fisted wrenching by someone using an impact wrench on the front sprocket/compensator nut...will most often cause the 2 crankshaft flywheels to eventually run out of phase and misalign themselves. End result is horrible primary imbalance causing excess vibration that can't be resolved.
    Wouldnt this reveal itself as excessive runout on the pinion shaft?

  6. #66
    Senior Member Cooter's Avatar
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    Codes (any code) won't make the ECM work differently (the problem that caused the code not-withstanding), and clearing them does nothing but re-set the counters.
    The AMC code wouldn't cause a vibration. IMO, safe to ignore it.

    I only mentioned 'in your head' because more than one of us has got back on a Buell after an extended time off one and thought WOW this vibrates a lot! Especially as they free decel. I can't think of anything else to check that would cause a vibration besides the things mentioned already. Timing wouldn't change, you say it still runs fast so I'd assume you'd know if you had a dead cylinder. They'll go 70 mph fairly easily on one cylinder Run it and make sure both head pipes at the head are hot? IR temp gun or spray a little water.

    I didn't re-read the whole thread, can you get in the ECM to see AFV or EGO correction? Both should be close to 100, no need to be exact, close is fine.

  7. #67
    Senior Member Cooter's Avatar
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    Quote Originally Posted by 34nineteen View Post
    Wouldnt this reveal itself as excessive runout on the pinion shaft?
    Ya, I would think a dial indicator on a mag stand would show it easily. Harbor freight sells them cheap and honestly not too bad a quality. We kill them often enough that expensive ones are, well... expensive

  8. #68
    Senior Member Nade's Avatar
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    If it is fitted with a Lunatic Fringe Ind. crank support, the vibration is probably from that. They were pre 1954? models only and prone to cracking (even with no pressure) or even from the bike falling off its stand. After an accident it will cause the crank to wobble and your ass with be out of phase to your toes.

  9. #69
    Quote Originally Posted by Cooter View Post
    Codes (any code) won't make the ECM work differently (the problem that caused the code not-withstanding), and clearing them does nothing but re-set the counters.
    The AMC code wouldn't cause a vibration. IMO, safe to ignore it.

    I only mentioned 'in your head' because more than one of us has got back on a Buell after an extended time off one and thought WOW this vibrates a lot! Especially as they free decel. I can't think of anything else to check that would cause a vibration besides the things mentioned already. Timing wouldn't change, you say it still runs fast so I'd assume you'd know if you had a dead cylinder. They'll go 70 mph fairly easily on one cylinder Run it and make sure both head pipes at the head are hot? IR temp gun or spray a little water.

    I didn't re-read the whole thread, can you get in the ECM to see AFV or EGO correction? Both should be close to 100, no need to be exact, close is fine.
    Hey Cooter, I've been messing with this for a while now as you know. The AFV is at 113 to 119. I've checked for intake leak using the propane method. I did a compression check on both cylinders and both were right at 120. I checked the injectors and re loosened and tightened the exhaust system.

    Now, if it was a problem with the crank, (I'm doubting but will listen) how would I confirm that?

    No CEL, no other problems other than a nasty engine vibration until 5k. I runs very well up there. Could a defective variable muffle motor give me such a big vibration?

    thanks

  10. #70
    Senior Member Cooter's Avatar
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    Quote Originally Posted by BuddyB View Post
    HThe AFV is at 113 to 119.
    Thats a bit high. not crazy... but high. Look at why that could be.

    Could a defective variable muffle motor give me such a big vibration?
    Nope.



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