SXR-800 possible Oil Water Mix in combustion chamber ???? - Page 2
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  1. #11
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    Re: SXR-800 possible Oil Water Mix in combustion chamber ????

    Quote Originally Posted by Felix #86 View Post
    ok but why is oil/water mix in the engine ? just bad head Gasket ? The Pictures are one year old at that time it was a paper head gasket since then i got an metal head gasket... i didnt open the engine since then..but ran fine all year... so i guess i need nothing more to do...
    Idk maybe. Probably nothing wrong with it if it was running well.

  2. #12
    I dream skis
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    Re: SXR-800 possible Oil Water Mix in combustion chamber ????

    SOoooo, just to be clear.... You were not having any trouble with the engine. You pulled the head, took the photos, got a new gasket, put it back together and it is running fine. Is that correct?

    There should be a bit of oil in the cylinder, that keeps it lubricated. There area few ways it can get water in the cylinder when you shut it off. You should fire it up for a few seconds while it is out of the water on the trailer. That blows water out of places it should not be.
    2, 1998 TS 770 L, restored and running great as of July 2019 (NO THANKS to the person at SBT, who put the WRONG crankshaft bearing into the rebuilt engine I got from them)

  3. #13
    PWCToday.com Is My Home Away From Home wmazz's Avatar
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    Re: SXR-800 possible Oil Water Mix in combustion chamber ????

    Quote Originally Posted by Felix #86 View Post
    Engine is NOT SEIZED.

    RUN perfekt 6800 rpm all day long.

    I just took the Head of to take alook nothing else. Ski ran fine. Pisser stream is steady.

    I sincerely hope you are correct.


    I could be wrong, but this is what I saw in your tiny picture:

    (1) A dark residue over the entire piston crown.

    (2) light (gray) color vertical patches near the transfer ports.


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



  4. #14
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    Re: SXR-800 possible Oil Water Mix in combustion chamber ????

    Quote Originally Posted by Felix #86 View Post
    ok but why is oil/water mix in the engine ? just bad head Gasket ?

    The Pictures are one year old at that time it was a paper head gasket

    since then i got an metal head gasket.
    First, head gaskets fail for a reason, Second composite (paper) head
    gaskets are the WORST because they increase the squish clearance
    .030" plus the deck height, plus the step in the combustion chamber
    (if there is one), and that increases the possibility for detonation.

    Was the head re-machined to increase the compression?

    Third, who knows what your compression is? It was ~30psi lower with
    that old paper head gasket.

    But it may have been a light seizure. If so a compression test would not
    show a difference, except for the ~30psi you gained with the oem head
    gasket.


    Bill M.

    After a year, the aluminum from the seizure may be worn away by the
    piston rings.

    Did you have a different set-up when the composite gasket blew?
    Maybe an impeller, pipe, or jetting?
    Last edited by wmazz; 10-27-2021 at 03:26 AM.
    Horsepower == Speed, RPM != Speed



  5. #15
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    Re: SXR-800 possible Oil Water Mix in combustion chamber ????

    ...
    Last edited by Felix #86; 10-28-2021 at 02:04 AM.

  6. #16
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    Re: SXR-800 possible Oil Water Mix in combustion chamber ????

    Quote Originally Posted by hemmjo View Post
    SOoooo, just to be clear.... You were not having any trouble with the engine. You pulled the head, took the photos, got a new gasket, put it back together and it is running fine. Is that correct?

    There should be a bit of oil in the cylinder, that keeps it lubricated. There area few ways it can get water in the cylinder when you shut it off. You should fire it up for a few seconds while it is out of the water on the trailer. That blows water out of places it should not be.



    Yes that is the Case. I fire the Ski up on the Trailer every time for 10 sec.

  7. #17
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    Re: SXR-800 possible Oil Water Mix in combustion chamber ????

    Quote Originally Posted by wmazz View Post
    First, head gaskets fail for a reason, Second composite (paper) head
    gaskets are the WORST because they increase the squish clearance
    .030" plus the deck height, plus the step in the combustion chamber
    (if there is one), and that increases the possibility for detonation.

    Was the head re-machined to increase the compression?

    Third, who knows what your compression is? It was ~30psi lower with
    that old paper head gasket.

    But it may have been a light seizure. If so a compression test would not
    show a difference, except for the ~30psi you gained with the oem head
    gasket.


    Bill M.

    After a year, the aluminum from the seizure may be worn away by the
    piston rings.

    Did you have a different set-up when the composite gasket blew?
    Maybe an impeller, pipe, or jetting?
    OEM Pipe
    OEM head

    Jetting is almost the same since that...
    But again the Pictures are from 2020... i didnīt open the Engine since that... Ski ran 6800 rpm all Day long... I run 50/1 Premix with fully synthetic TCW3 oil.
    I think my jetting is a bit rich, spark plugs are dark Brown/Black also.... maybe thats why the Pistons are this Color....

    I can test Compression later today....

  8. #18
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    Re: SXR-800 possible Oil Water Mix in combustion chamber ????

    Cold Engine

    #1 155 psi
    #2 150 psi
    Last edited by Felix #86; 11-09-2021 at 03:00 PM.

  9. #19
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    Re: SXR-800 possible Oil Water Mix in combustion chamber ????

    Maybe i bring the head for milling. Then i am sure it is flat as hell

    can i cut off 0,020" out of it to gain sime more psi ?

  10. #20
    PWCToday.com Is My Home Away From Home wmazz's Avatar
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    Re: SXR-800 possible Oil Water Mix in combustion chamber ????

    Quote Originally Posted by Felix #86 View Post
    Cold Engine

    #1 155 psi
    #2 150 psi
    Quote Originally Posted by Felix #86 View Post
    Maybe i bring the head for milling. Then i am sure it is flat as hell

    can i cut off 0,020" out of it to gain some more psi ?
    Stock compression on the SXR is ~175psi. But many people do
    not have accurate compression gauges. The rear cylinder was
    5psi low, and that is concerning. But again it may be low because
    you didn't test it exactly the same as the front cylinder. It should
    be retested with a fully charged battery, wide open throttle, and
    keep testing until the compression gauge levels out completely.

    There is usually about a .010" step in the head, and removing
    that step will get you about ~10psi in addition to the stock
    compression. Which is close to the recommended pump gas
    limit of 185psi.

    A better modification is to measure the squish and reduce it to
    .040". It will increase the compression, acceleration and decrease
    the possibility detonation. But if you keep your compression at 185,
    it may require the domes remachined. This is a job for a shop or
    machinist with experience since the cylinder deck height will be
    cut.


    Bill M.

    The reason I worry about a 5psi difference between cylinders is
    because a seized engine is capable of recording the same compression
    on both cylinders despite the seizure. A lower reading on 1 cylinder has
    a cause. It isn't a clunker car engine, don't apply car rules of thumb
    to your watercraft.
    Horsepower == Speed, RPM != Speed



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