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  1. #1
    resident guru 87kawi650sx's Avatar
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    650 pistons in 550 reed cylinder?

    I purchase a 550 crank with IMS pro series rods which i thought was for 550 pistons, but the holes for the wrist pin and bearing are too big. 550 wrist pin bearings are 14mm, 650 wrist pin bearing are 16mm, and the crank is about 2mm to big. im assuming the crank may be made to accept 650 pistons. has anyone ever done this? Are 650 pistons longer then 550 pistons? in other words, would i need a stroker plate? Any information would be appreciated! im building this ski as part of my senior project so it need to be ready for may 17.
    91' js440 hull- PJS T3, PJS head (190 psi), Pjs exhuast mani, PJS intake mani, dual cdk taper bored 40's, 440 blue printed/honed pump, ocean pro nozzle, 18* prop, all the bolt-ons besides ignition.

    Under the knife: 87' 300sx hull with 550sx reed motor, Jetinetics charging flywheel blue-printed 440 pump off of a R&R JetTec ski, 16.5 solas supra prop, ocean pro reduction nozzle, pjs 2500 full pipe, inline silencer, SBN44, fmf reeds, milled head, all the bolt-ons.



  2. #2
    Top Dog Bruce in SB's Avatar
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    Re: 650 pistons in 550 reed cylinder?

    I think 650 wristpins are 18mm not 16..
    "Thanks" to Chris Newmiller @ Newmiller Machine

  3. #3
    resident guru 87kawi650sx's Avatar
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    Re: 650 pistons in 550 reed cylinder?

    hmm, maybe 550 wrist pins are 16? i looked it up in a parts catalog today and remember there was a 2mm difference.
    91' js440 hull- PJS T3, PJS head (190 psi), Pjs exhuast mani, PJS intake mani, dual cdk taper bored 40's, 440 blue printed/honed pump, ocean pro nozzle, 18* prop, all the bolt-ons besides ignition.

    Under the knife: 87' 300sx hull with 550sx reed motor, Jetinetics charging flywheel blue-printed 440 pump off of a R&R JetTec ski, 16.5 solas supra prop, ocean pro reduction nozzle, pjs 2500 full pipe, inline silencer, SBN44, fmf reeds, milled head, all the bolt-ons.



  4. #4
    Top Dog littleman456's Avatar
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    Re: 650 pistons in 550 reed cylinder?

    I think at some point (and correct me if I'm wrong) PJS had an IJSBA race boat that was a 550 that they had pressed 650 sleeves into, and thus converted it to a 650. Now obviously PJS had a lot more time/money into there engine but maybe you could find some info on it somewhere. This is just a rumor I once heard, but maybe you could do the same thing, I know it would be one screaming ski if you got it to work though!

    Good luck,
    Chase
    '85 550/750/X2 pump swap -In Progress
    "If it's electrical, mechanical, or a woman,
    it doesn't need to make any sense."

    Quote Originally Posted by tensecrnr View Post
    we dont live and ride sometimes we ride and live a little...
    Quote Originally Posted by WFO Speedracer View Post
    you are trying to reinvent the wheel, that one isn't gonna roll.
    P.M. if your looking for: Full 650 engine and electronics, Yellow 580 parts, or Tide rider parts/info

    Fueled by two stroke, Dr. Pepper, and Hank Williams

  5. #5
    resident guru 87kawi650sx's Avatar
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    Re: 650 pistons in 550 reed cylinder?

    thanks chase, and thats another questions, would i need to resleeve it with 650 sleeves? or would i just be able to bore it to 76mm (stock 650 size) and put 650 pistons in.
    91' js440 hull- PJS T3, PJS head (190 psi), Pjs exhuast mani, PJS intake mani, dual cdk taper bored 40's, 440 blue printed/honed pump, ocean pro nozzle, 18* prop, all the bolt-ons besides ignition.

    Under the knife: 87' 300sx hull with 550sx reed motor, Jetinetics charging flywheel blue-printed 440 pump off of a R&R JetTec ski, 16.5 solas supra prop, ocean pro reduction nozzle, pjs 2500 full pipe, inline silencer, SBN44, fmf reeds, milled head, all the bolt-ons.



  6. #6
    PWCToday.com Is My Home Away From Home MrSki's Avatar
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    Re: 650 pistons in 550 reed cylinder?

    Quote Originally Posted by littleman456 View Post
    I think at some point (and correct me if I'm wrong) PJS had an IJSBA race boat that was a 550 that they had pressed 650 sleeves into, and thus converted it to a 650. Now obviously PJS had a lot more time/money into there engine but maybe you could find some info on it somewhere. This is just a rumor I once heard, but maybe you could do the same thing, I know it would be one screaming ski if you got it to work though!

    Good luck,
    Chase
    This is no rumor. Jeff Jacobs ran stroked and bored motors using 650 pistons. FlynTy on this board, lives around the corner from me, procured one of Jeff's old race boats and found all this in the motor. Could be our poster here found a special crank.
    1992 550 SX - R&R port Kawi Reed, Kind of fast.
    1989 JS 550 - PJS motor Dual 46's, 50 MPH on GPS.
    1986 JS 550 - Engine built. On to fiberglass!
    1976 JS 400 - Pretty much just a shell.

  7. #7
    resident guru 87kawi650sx's Avatar
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    Re: 650 pistons in 550 reed cylinder?

    Thanks for the info M. Ski, ill have to talk to ty about that motor...If anyone has and junk 650sx pistons woth wrist pins and bearings they want to let go for cheap let me know!

    The stroke on this crank it is stock, i did put the motor together and the pistons did not hit the head.
    91' js440 hull- PJS T3, PJS head (190 psi), Pjs exhuast mani, PJS intake mani, dual cdk taper bored 40's, 440 blue printed/honed pump, ocean pro nozzle, 18* prop, all the bolt-ons besides ignition.

    Under the knife: 87' 300sx hull with 550sx reed motor, Jetinetics charging flywheel blue-printed 440 pump off of a R&R JetTec ski, 16.5 solas supra prop, ocean pro reduction nozzle, pjs 2500 full pipe, inline silencer, SBN44, fmf reeds, milled head, all the bolt-ons.



  8. #8
    resident guru 87kawi650sx's Avatar
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    Re: 650 pistons in 550 reed cylinder?

    heres a picture of the crank with the bearing http://www.pwctoday.com/showthread.php?t=366555
    91' js440 hull- PJS T3, PJS head (190 psi), Pjs exhuast mani, PJS intake mani, dual cdk taper bored 40's, 440 blue printed/honed pump, ocean pro nozzle, 18* prop, all the bolt-ons besides ignition.

    Under the knife: 87' 300sx hull with 550sx reed motor, Jetinetics charging flywheel blue-printed 440 pump off of a R&R JetTec ski, 16.5 solas supra prop, ocean pro reduction nozzle, pjs 2500 full pipe, inline silencer, SBN44, fmf reeds, milled head, all the bolt-ons.



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