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Thread: Engine shake during RPM drop

  1. #11
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    Of course! On the XB, only a few days. But I've been on other V-twins (smaller displacement - 649, 821, 1098) that I never noticed that on before. 1203 cc V-twin is definitely a lot different and a lot more piston to move so I'm not surprised that it has that slight shuddering characteristic. Most of my riding experience comes from 599 cc I-4 bikes though.

  2. #12
    Senior Member Silverrider's Avatar
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    Yea, Ducs & 599 cc I-4 are different 1203 cc V-twin for sure.

  3. #13
    Senior Member rchuff's Avatar
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    It all has to do with balanced and not so balanced crackshafts.
    Last edited by rchuff; 07-08-2018 at 05:21 PM.

  4. #14
    Senior Member Chicknstripn's Avatar
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    Sounds like you’re expirencing the same thing I did when I went from a 2003 Honda VFR to a 2007 Buell back in 2007! At the time my brother was an HD mechanic and parts rep. I would call him, when I first got the bike, and ask him if certain neuances I was feeling with the Buell V-twin were normal. I was especially concerned with the transmission, going from a Honda to a Buell redefines Japanese engineering.

    To get back on track, sounds like your engine/bike is perfectly normal.

    Bearing in mind how much the bike does shake and rattle it’s a good idea to periodically check all the fasteners and bolts you possibly can. Parts have been know to rattle themselves to freedom!

  5. #15
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    Quote Originally Posted by Chicknstripn View Post
    Bearing in mind how much the bike does shake and rattle itís a good idea to periodically check all the fasteners and bolts you possibly can. Parts have been know to rattle themselves to freedom!
    Yeah I was surprised to see how many times loctite is mentioned in the service manual compared to my zx6r service manual lol but yeah I'll keep an eye on things, thanks!

  6. #16
    Senior Member mmcn49's Avatar
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    Had vibrations, not really a shake, on my new 07. Map tunes, smoothing out the lean dip a bit, correctly doing a TPS reset and setting the idle just under 1000 smoothed things out considerably. It only vibrates around idle now and just a little.

  7. #17
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    Mine doesn't seem to have any odd vibrations while cruising, its actually really smooth. Pretty sure the engine shake during rpm drop is due to the single-pin crank shaft design and like rchuff said, it not being very well balanced.

  8. #18
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    Hey rtrofimovich, I noticed the exact same thing. Engine runs great, upshifting and downshifting are smooth. Just if I pull the clutch in to coast or slow down. Kind of a 1 second shudder that I can feel mostly in my head. Maybe the vibrations are going up my arms. And my bike's only the xb9 so smaller cylinders and less vibration I would think. I replaced the primary tensioner and primary fluid, seemed to reduce it a bit but not much. Just another quirk.

  9. #19
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    Yeah I think it's not so much engine/piston size as it is the single-pin crank design. It's naturally sort of "off-balance" so a little shaking would seem normal. As long as it's not shaking while cruising I got no worries

  10. #20
    Member herwawan's Avatar
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    I do have a similar feeling, when I release the clutch and the RPM drops around 2k - the whole bike vibrates more right at it, not much before, not much after. I mainly notice it because my rear mirrors are a bit loose and they shake like it's a earthquake with all the shaky noises that go with it.

    I simply assumed it's part of it, anyways that thing is vibrating all the time - a little bit more or a little bit less won't make much change.



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