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Thread: bad vibration

  1. #1
    Junior Member nixdsg's Avatar
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    Hello, been on this site for some time, mostly looking (lost my log in?), but been here since 2005.



    I need HELP!

    I have a 2005 TW, ~1300 miles, bought it new. Put on about 600 miles this summer.

    Riding home from work, 15 mile into a 20 mile ride at ~55 mph, the bike starts to vibrate BAD. Thinking the tires are chunking and coming apart I pull in the clutch. Vibration goes away, tires look good, .... In trafic I let out the clutch and accelerate (with excessive vibration) till I can pull off. Stop bike and it idles fine. no smoke, oil in the window,... revs fine. Get back on to go home and the vibration goes from nothing, to bad at mid rpm, to minimal/normal at higher rpm. Power seems the same. accelerate up to 70 mph with minimal vib. Hummm.



    Testing at home the vibration occurs in all gears at mid rpm. OK at low, power is good, then as rpm's build the vib is bad, then seems to smooth out. This happens in ALL gears. This happens with clutch pulled in regardless of gear or not.



    changed oil, normal. no metal, bronze, chunks, ... Filter is clean (normal few small pieces). Tires look good, don't wiggle side to side. Chain is tight enough. wheels spin fine.



    opened left side engine cover, flywheel looks right and hasn't appeared to have shifted. Timing looks ok, but not perfect, maybe 1/4 to 1/2 tooth off?? Again, doesn't surprise me. Opened cam and front rocker covers: timing chain is rather tight, no way it jumped a tooth. rocker arm looks good but didn't check gap. No metal shavings or anything indicating the come aparts.



    Idea's??



    Nic

  2. #2
    Senior Member lizrdbrth's Avatar
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    First check the motor mounts.



    Check the flywheel again. Turn the bolt slowly, looking far any out-of-round condition. You may want to retourque it and also make sure the keyway is in position. Lift it with a prybar and see if there's any movement in the crank. Slowly reverse it looking for noises which would indicate rod bearings.



    Then check your clutch basket. The fact that it only occurs under load and in gear suggests something in the rotating assembly has gone south.



    I can explain it to you, but I can't understand it for you.

    Powdercoated '87 frame, extended swingarm, YZ fork legs, ATV tire, 14/55, XT350 tank, spliced quick-release seat, disc brake conversion, beeg headlight, beeger rack, Lizrdcooler, Lizrdventz and bunch of other stuff all covered in invisible ink.

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  3. #3
    Junior Member nixdsg's Avatar
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    " suggests something in the rotating assembly has gone south", YA, that's my concern. But there is no visable bearing or metal material showing bad things are happening???



    I'll get after the clutch when I have time to take it apart. Ugh.



    What about the counter balancer coming undone? Can the drive gear come unscrewed from that shaft? Can the key come out???



    Nic

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  5. #4
    Senior Member lizrdbrth's Avatar
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    Balancers have been known to break or even jump teeth the same as a cam will. You got something goofy and along those lines going on in there.



    I can explain it to you, but I can't understand it for you.

    Powdercoated '87 frame, extended swingarm, YZ fork legs, ATV tire, 14/55, XT350 tank, spliced quick-release seat, disc brake conversion, beeg headlight, beeger rack, Lizrdcooler, Lizrdventz and bunch of other stuff all covered in invisible ink.

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  6. #5
    Junior Member nixdsg's Avatar
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    Well...



    Engine mounts are tight

    Clutch looks good (plates and parts)

    Balance shaft is keyed properly, bolts tight, and lined up to crank gear properly

    As best I can tell there are no "loose pieces" in the crank case, kinda hard to see in there



    What next?

    Would a bad CDI do this?



    Nic

  7. #6
    Junior Member nixdsg's Avatar
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    Update



    I talked to a torsional vibration expert at work today, and he convinced me that what I'm discribing was a loose engine mount or worse, something broke (mount, frame, ...). He said an engine issue would mean a 1st order vibration which would have increased intensity with rpm, that is not what is happening. To him, what I discribed would be something loose/broken in the mounting system. So....



    I started looking closer at the crame, mounts, ... And guess what, looking at the top mount, where the head attaches to the frame, the bolt from the bracket into the head was OK, I checked that torque last noght, but.... When I looked closer, I saw that the top two bolts, from the top bracket to the frame (up under the tank) was missing!!! Really? I took off the tank and sure enough, you could see the impression from the bolt heads in the bracket but NO BOLTS! Wow, where the heck did those go?? I've never removed or loosened those bolts. SO, bolts added, now I need to get the engine case gaskest to close things back up before I verify that it's all fixed.



    Thanks for all you help, I'll post again when the solution is comfirmed!



    Nic

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