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  1. #1

    SLTX Compression.. is this bad?

    Got my entire motor rebuilt...

    Took it out for 1 hour, realized it was way to lean, also had a clogged exhaust manifold to exhaust exit tube clogged...

    Anyways, I think I blew the front cylinder...

    Did a comnpression check

    MAG 90 MIDDLE 120 PTO 120

    what do you think? blown?

    Arent the 120's a little low too? I was thinking they should be more like 150, but maybe not on this model.

    Its a 1996 SLTX 1050.. red motor.


  2. #2

    Help please.. Compression results SLTX 1050

    Just got my motor rebuilt.

    Ran it for 1 hour, ran bad, realized the cylinders were starving for air, very very lean.

    I did a compression test to see if I blew anything.

    MAG 90 MIDDLE 123 PTO 123

    This is a 1996 SLTX 1050 red motor

    Is the 90 that bad that I should take the cylinder off, or should I see what happens when I fix the lean condition?

    Also are the 123 low? This is a brand new top end rebuilt, from a very good shop that put this together.....

    Thanks for any help you can give me..

  3. #3
    I've heard that you don't want more than around 10 psi difference between the cylinders.

    My two 1997 SLTX 1050's with ~120 hours are:

    130, 120, 130

    128, 119, 127

    Btw these were checked when the engine was cold.

  4. #4
    Rasta Mon Condoms We Be Jammin!!!!! TxVirageTx's Avatar
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    psi

    if your positive that 90 is the best reading you'll get,your gonna have to redo that cylinder,at least hone and rering

  5. #5
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by motox1027 View Post
    Got my entire motor rebuilt...

    Took it out for 1 hour, realized it was way to lean, also had a clogged exhaust manifold to exhaust exit tube clogged...

    Anyways, I think I blew the front cylinder...

    Did a compression check

    MAG 90 MIDDLE 120 PTO 120

    ...Arent the 120's a little low too?
    I was thinking they should be more like 150, but maybe not on this model.

    Its a 1996 SLTX 1050.. red motor.
    Have you downloaded the Service manual from here?

    Polaris spec says the cylinders should have 10 percent or less difference from the best to the worst.

    Compression is tested with the throttle held wide open, all spark plugs removed, and battery delivering over 10.5 volts while cranking (healthy battery).
    Is this how you did it?

    Since this is a new top end rebuild, the rings may not have seated correctly. That said, the pressures you listed are too different to be good.

    What break-in procedure where you using?

    Why was it running so lean?

  6. #6

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    90 is no good , you want your clys to be above 120 for max performance , i think they'll pop up with a proper break ing , you might wanna take the cly domes off that weak cly and see if a ring bit the dust or you have premature wear , you can rotate the crank till the piston is half way down take you finger see if the rings move side to side much


    follow this http://www.angelfire.com/zine2/boost...ur-PWC%21.html

  7. #7

    re

    I had the throttle wide open when testing, plugs out.

    Looking through the plug hole, the cylinder with 90 psi, well the piston looks rusy on top, like it got burnt.

    I am just going to replace it, after doing one more compression test to confirm its bad,

    I am almost sure the reason was it was running to lean. The plugs, has like no gas on them. Lean is like the only thing that would do this....

    I dont know why iots running lean. I cleaned the carbs before this, and internal filters, they were clean upon taking them apart as a note...

    I dont have the older style gas line.

    I am guessing on a clogged gas line, petcock on - off valve, or a T connector?

    Does that sound right?

    I was thinking maybe the fuel pumps, but when the ski is off, and I give it gas, all 3 pump gas into the top throat part of the carb, so i am assuiming they are good.

  8. #8
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by motox1027 View Post
    ...I am guessing on a clogged gas line, petcock on - off valve, or a T connector? ...
    The petcock and all the supply fuel lines from the tank to the fuel pump are under suction, not pressure, when the engine is running.

    Make sure the petcock (fuel selector valve) is not leaking air into the fuel system. If the valve O-ring seals (or anything else) leaks air into the fuel supply line, the carbs won't get the fuel they need.

    As engine RPM rises under load (on the water), the carbs need more fuel, and the fuel pump pumps harder, creating a stronger suction to the tank. If that causes more air to leak into the fuel lines, the carbs will run leaner.

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