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  1. #1
    PWCToday.com Is My Home Away From Home Bruce in SB's Avatar
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    Yamasaki vibration ??

    I built a 1992 550 SX hull with a 701 62t out of a Raider. Super clean motor and never been apart. I used a Rhass Yamaha engine conversion kit and his 750 pump kit.
    It also has a Superjet FPP B Mod pipe and Superjet waterbox with a full 1/8" clearance all around everything.
    Problem is it has a terrible just "off- idle" vibration that is super annoying. The regular idle is sweet and past the vibration is super smooth as well. Spent a lot of time looking at clearances everywhere including the spots by the battery ribs and the diagonal front corner.
    Rhass suggests it will go away with time. Also suggests that the big rubber block under the motor, when it was in the Raider, was an emergency motor support not a harmonic damper.
    Tonight on the stand I noticed a severe lateral vibration of my fuel tank as the motor transitioned thru the bad rev zone.
    Any one have any ideas?
    Does the 62t need a special flywheel balance? Motor mounts too hard or too soft? Pipe have a harmonc spot?
    Other than this vibration, it should be a cool set-up
    Thanks for any ideas
    "Thanks" to Chris Newmiller @ Newmiller Machine

  2. #2
    PWCToday.com Is My Home Away From Home Bruce in SB's Avatar
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    Re: Yamasaki vibration ??

    BTW... I ran this motor and hull with a nice tested 550SX pump and 20" prop and had the same vibration... so I am thinking it is not a driveline whip ... but maybe ??
    "Thanks" to Chris Newmiller @ Newmiller Machine

  3. #3
    PWCToday Guru dose's Avatar
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    Re: Yamasaki vibration ??

    Mine does the exact same thing!!!
    I thought it may be the water box and I put extra turf around it but didn't change anything
    I have that rubber thing on the bottom too but double checked it has good clearance,
    I have just learned to live with it
    another guy posted he was rubbing by where you trim the 550 battery area was rubbing, I have clearance there too so I just been running it with the vibes
    super couch
    550sx with 701 and big pump
    550 RC-520
    809cc X2

  4. #4
    PWCToday.com Is My Home Away From Home Bruce in SB's Avatar
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    Re: Yamasaki vibration ??

    Yeah ... "Cudaben" had the same problem with a Yamaha in an X2 which makes me think it is the motor mounts somehow.
    Bump
    "Thanks" to Chris Newmiller @ Newmiller Machine

  5. #5
    PWCToday.com Is My Home Away From Home wmazz's Avatar
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    Re: Yamasaki vibration ??

    So this happens on the stand and in the water?

    I had a Yamaha 1100 almost rip itself off my dyno one time.
    At the time I thought it was the soft motor mounts. But maybe
    that big engine coupler is partially to blame?


    Bill M.
    Horsepower == Speed, RPM != Speed



  6. #6
    PWCToday.com Is My Home Away From Home Rushford_Ripper's Avatar
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    Re: Yamasaki vibration ??

    Everything shimmed correctly? I cut that rubber under engine damper basically off on my 6m6 conversion I just built (having a fuel/running issue at the moment.) I'm curious to see if I get the same vibration....


  7. #7
    PWCToday.com Is My Home Away From Home Grumpy Old Guy's Avatar
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    Re: Yamasaki vibration ??

    Once you take the stock pipe off a Yamaha motor they will shake like a paint mixer,add Rhass motor mounts & its worse.

    Its not gonna get better.
    Last edited by Grumpy Old Guy; 04-29-2017 at 12:25 PM.

  8. #8
    PWCToday.com Is My Home Away From Home Myself's Avatar
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    Re: Yamasaki vibration ??

    I'm also betting if you look at rpms it will vibrate severely again at exactly double that rpm. Typical 2 stroke behavior with a 180 twin. It would be very expensive but the whole rotating assembly could be balanced. Maybe somebody should offer a PTO damper like a tci "rattler".
    Last edited by Myself; 04-29-2017 at 12:37 PM.
    http://www.facebook.com/twinlakesjetskirepair

    '89 Kawi 650SX 42.4 GPS
    +3" stock pipe, ported ex. manifold, drilled waterbox, blueprinted pump, Ocean Pro ride plate

    '99 Yama GP1200 65U 61.8 GPS
    ported cylinders, matched cases, milled head, blueprinted pump, long ride plate

    '96 Seadoo HX 717 53.13 GPS
    light porting, massaged cases, lightened flywheel, port matched manifolds, Rossier pipe, stubby pump cone

  9. #9
    PWCToday.com Is My Home Away From Home Grumpy Old Guy's Avatar
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    Re: Yamasaki vibration ??

    Seadoo had a vibration issue with the 720 when they went from the steel bed plate to mounting ears off the engine.....The engine had vibration so bad it was breaking the bolts holding the exhaust pipe on (8mm) & went to a 10mm bolt to keep from breaking the bolts.

  10. #10
    PWCToday.com Is My Home Away From Home Rushford_Ripper's Avatar
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    Re: Yamasaki vibration ??

    I've heard of this vibration even with the stock pipe in the conversion skis. You say its the motor mounts? What makes you believe this? Just wondering....


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