750, will 800 cylinder fit?
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  1. #1
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    750, will 800 cylinder fit?

    Will be rebuilding my top end by the end of the year. I thought I remember someone saying I could run 800 sxr cylinders on a 750 BP case. Correct me if I'm wrong. Thanks!

  2. #2

    Re: 750, will 800 cylinder fit?

    Yes, you can.
    Last edited by 2strokesmoke; 07-10-2019 at 03:41 PM.

  3. #3
    PWCToday.com Is My Home Away From Home theVetteman3's Avatar
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    Re: 750, will 800 cylinder fit?

    The 800 cases are 750 big pin cases with additional finger cuts machined in for case porting.
    1985 JS550/800 "Pretty Red": Newmiller 800, Rhaas 750 pump conv. [56.3mph gps]
    2009 1100 SJ:
    Kawi 1100 build in progress
    2009 SJ MINT:
    KP steering adaptor, Worx 228 intake [45.8mph gps]
    1987 WJ650:
    6M6, JD Intake Grate, 17/20, cheater pipe [47.8mph gps]
    1994 XiR: 830cc Superstock, PJS side draft, 13/18 swirl [53.7mph gps]
    1995 SJ MINT:
    [TBD]



  4. #4
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    Re: 750, will 800 cylinder fit?

    Im also curious about this. Is there much gain over a 762 cc cylinder? Is it worth the swap. Another 40cc of displacement seems like it would be “felt” power


    Sent from my iPhone using Tapatalk Pro

  5. #5
    Top Dog Benflynn's Avatar
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    Re: 750, will 800 cylinder fit?

    I think it’s about the port timing

  6. #6
    PWCToday.com Is My Home Away From Home theVetteman3's Avatar
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    Re: 750, will 800 cylinder fit?

    The port timing on the 800 cyl is similar to the lime green head small pin. Middle of the road between low end (750sx cyl) and high end (big pin / pro cyl). To my knowledge that just made the cylinder a bit more efficient I don't think the port timing actually gained power. Might have improved the power torque curve but not peak.

    The 800s were rated at 80hp and the 750 dual carbs 75. I know the CC and case porting helps, I'm not sure if that's the full extent of the gains. Maybe a bit from the exhaust? The chamber is different. Others with more knowledge can step in here.

    So is it worth it. This is a big "it depends". I have two actual ported 800s. One superstock ported, one freestyle. I'm building up an engine for my sxi pro now which is the oem big pin bottom end with a freestyle ported 750sx cyl. For general rec riding my thought is the 750sx cyl when equivalently ported probably "feels" stronger down low than the 800s. That low port timing really helps. I'll be able to say definitively in a few weeks. And this is all subjective, and how the cylinders are ported can make a big difference for how each cyl feels. It's much easier to feel low end. Mid range can be hard to compare because it depends on when your pipe hits and lots of factors. So unless you run your exact ski with the 750 cyl and then the 800 cyl back to back, it might be hard to tell if you can feel true differences between the cyls.

    If you case port the 750 cases, and use a 800 cyl, you'd be no worse off hp wise from the true full 800 engines.
    Last edited by theVetteman3; 07-16-2019 at 07:19 AM.
    1985 JS550/800 "Pretty Red": Newmiller 800, Rhaas 750 pump conv. [56.3mph gps]
    2009 1100 SJ:
    Kawi 1100 build in progress
    2009 SJ MINT:
    KP steering adaptor, Worx 228 intake [45.8mph gps]
    1987 WJ650:
    6M6, JD Intake Grate, 17/20, cheater pipe [47.8mph gps]
    1994 XiR: 830cc Superstock, PJS side draft, 13/18 swirl [53.7mph gps]
    1995 SJ MINT:
    [TBD]



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