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98 SLH 700 issue

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  • #1

    98 SLH 700 issue

    I have a 98 Polaris SLH. About two years ago the oil injection stopped working, so I replaced the engine with an SBT unit. I pre mix fuel now.

    The engine has never had the power it used to. I used to be able to see 6800-6900 rpm, now I'm lucky to see 6600. It used to read up to 58mph on the MFD, 50 is about best now (I know they aren't accurate, it's just a comparison). It used to be able to run right next to my buddy's Wave Raider 1100 top end, and rip him out of the hole. Not a chance in the world now.

    It will not get up on plane without tons of choke. It will not idle continuously without choke (the rpms drop slowly until it's dead, takes about 15 seconds). Throttle response is sluggish at best. Letting anyone else ride it is NOT an option, they are sure to get stranded somewhere.

    I took the carbs (dual carb model) off and had the dealer go through them. Not a single improvement.

    I replaced the reeds. Again, zero improvement.

    I installed an electric fuel pump to see if fuel delivery was a problem. Apparently not.

    Compression is 120 on both, and has been since I installed the engine.

    The need for choke leads me to believe there's an air leak somewhere, but doesn't necessarily explain the lack of power. Usually lean motors run real good until they melt a piston:-)
    Last edited by MattPark; 05-21-2006, 04:44 PM.
    Tags: None
  • #2
    Re: 98 SLH 700 issue

    I'll double check the Manual Monday, I don't recall what the top RPM is supposed to be for a Polaris 700. 6800 seems high off the top of my head, but I'm not 100% sure.

    120, if an accurate reading, is low. Normal compression should be about 145. If it's still under warranty please call in and we'll get you a new one.
    SBT Tech Support is here to help with your problems.
    We try to answer each question quickly and accurately.
    Please do not use Private Messaging for Tech Support, use the forums.

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    • #3
      Re: 98 SLH 700 issue

      I just pulled out my warranty registration, engine was purchased on 9/5/02. Looks a bit out of warranty.

      Like you, I don't have a manual here, but was thinking that was about right on for compression. I think that's what my other motor was before it left me stranded (I had some heads shaved and was comparing compression numbers. I have not taken the heads off the SBT engine).

      The engine probably only has 40 hours on it since I installed the engine (it's no fun to ride, and I have a boat). The original motor was fine to 250 hours, before the oil injection stopped working.

      I don't think the engine itself is the problem. It seems like a huge mixture issue, at all RPMs. Maybe a crank seal isn't positioned correctly or something, and letting air in. Is there a way to test for leaks? I'd imagine the intake and exhaust would have to be blocked off somehow.

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      • #4
        Re: 98 SLH 700 issue

        Check your carb settings. Also check your impeller for ease of rotation. This can be done withe the spark plugs removed and rotate the drive shaft. Or remove the pump and check the bearings.
        http://server1.sbtontheweb.com/forum...ad.php?t=13981

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        • #5
          Re: 98 SLH 700 issue

          Just checked both (I have checked before), both were/are right on at 1 7/8. Would it be a good idea to back them out a bit more?

          It seems like it might run on one cylinder at times at low rpm, adjusting them both differently might be a pain.

          How do the low speed jets affect mid and full throttle power? Is fuel still flowing through them or does it switch over to only the high speed jets?

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          • #6
            Re: 98 SLH 700 issue

            To check for an air leak, idle the ski on the trailer and spray starting flued around the seals and carb bases. Yes, 3 years out of way past warranty service. If the ski is stock, the carbs should be at the stock settings. If it doesn't run correctly then something is wrong.
            SBT Tech Support is here to help with your problems.
            We try to answer each question quickly and accurately.
            Please do not use Private Messaging for Tech Support, use the forums.

            Comment

            • #7
              Re: 98 SLH 700 issue

              Originally posted by MattPark
              Just checked both (I have checked before), both were/are right on at 1 7/8. Would it be a good idea to back them out a bit more?

              It seems like it might run on one cylinder at times at low rpm, adjusting them both differently might be a pain.

              How do the low speed jets affect mid and full throttle power? Is fuel still flowing through them or does it switch over to only the high speed jets?
              The low's are always in play but the fuel always tokes the path of least resistance. I would disasemble the carbs just to make sure they are clean. Also check fuel lines for blockage and obstructions. replace if needed.:emoticont

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