SBT Jetski Engines, Parts & Accessories

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  1. #1
    Joined
    Aug 2001
    From
    Iowa
    Posts
    16

    Post

    I recently installed a SBT motor in my 1994 SL 750. The new motor doesn't have as much power as previous one had. The ski tops out at about 40 mph and the rpm tops out at 5200-5400. The machine doesn't bog it just lacks power and responsiveness.

  2. #2
    Joined
    Feb 2001
    From
    Clearwater, FL
    Posts
    7,373

    Post

    Take a good compression gauge and check the engine - you shoul dhave around 120 psi on each cylinder.

    Beyond that, check your reeds, make sure you are using the right plugs, the carbs are clean and functioning...

  3. #3
    Joined
    Aug 2001
    From
    Iowa
    Posts
    16

    Post

    I checked my compression and it reads around 95 psi in all cylinders. Should I hone the cylinders and replace the rings?

  4. #4
    Joined
    Feb 2001
    From
    Clearwater, FL
    Posts
    7,373

    Post

    No, you should get an accurate gauge.

  5. #5
    Joined
    Aug 2001
    From
    Iowa
    Posts
    16

    Post

    I checked the guage on a slx and the compression is around 120 in all cylinders, so it for sure works.

  6. #6
    Joined
    Feb 2001
    From
    Clearwater, FL
    Posts
    7,373

    Post

    Give me your serial number - it's on the engine stamped on the front of the heads - and printed in your owners manual. I will lookup what that block left here testing at.

  7. #7
    Joined
    Nov 2001
    From
    Wisconsin
    Posts
    57

    Post

    Make sure your holding the throttle open while checking compression. Not sure it can effect reading as much as 25psi thou...

    Tim

  8. #8
    Joined
    Apr 2002
    From
    Fort Wayne Indiana
    Posts
    84

    Post

    How much running time do you have on the engine? What elevation are you! The best way to check for a bad seal on the rings would be to do a leak down test Not a compression test. Did you run it without any premix oil in the fuel. You can "wash the cylinders" and destroy the rings in a matter of seconds if the cylinders are run dry. I would agree that 95lbs seems a litlle low but A compression test is not always the answer. I suggest that you call SBT and ask them to help you figure out what could be wrong. I am sure they will address your problem without delay

  9. #9
    Joined
    Aug 2001
    From
    Iowa
    Posts
    16

    Post

    Brian,
    My SBT serial number is 13038.

  10. #10
    Joined
    Feb 2001
    From
    Clearwater, FL
    Posts
    7,373

    Post

    That particular block blew 125 here on the test stand before it shipped.

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