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  • #1

    No power

    Last winter, I replaced the engine in my '95 XP. Reason for replacement was broken rotax valve. All seemed fine. Yesterday, launched for first time. Ran fine out of the water but would stall in the water. Finally got it to stay running by keeping very slight throttle. Then it died and again would not start in the water.

    Prior to the rotax valve problem, everything ran fine. Carbs, etc. were not touched during the rebuild.
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  • #2
    Re: No power

    Is this an SBT engine, and were they stock rotary valves?
    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: No power

      You asked if the rotary valve was from SBT. I installed an SBT 717 engine a few weeks ago and reused the oem rotary valve and cover plate which were in good condition. Timed for 147 degrees. Runs great. Question: Is there a difference between SBT rotary valves and oem valves?

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      • #4
        Re: No power

        Let's clarify terms...

        what are you calling a rotax valve? There is a rotary valve, and RAVE valves. I asked about the rotary valve to see if you were using carbon aftermarket rotary valves. Our valves are just like OEM.

        If it's a RAVE valve you meant, that broke, that's a different story.

        If this ski has been sitting since last winter, I would strongly suggest rebuilding the carbs, getting out all the old fuel and starting fresh.
        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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        • #5
          Re: No power

          Sorry. Yes, it is an SBT engine. I was trying to make it clear that the ski had been running well prior to the engine failing. The failure was apparently due to a rotating part in the bottom of the block (per the dealer). I was trying to recall the name for the part that the dealer thought had failed. Don't know why I wrote valve, it is not. It is not the rotatry valve, which is OEM. The shaft would turn in one direction but not the other. Nothing on the carbs, etc. was touched.

          It starts easily out of the water. But it will not start in the water. The only way to get it going is to lift it from the water, start it, add slight throttle, and lower into the water. Since it is a new engine, we have not tried to rev it under load.

          I am confident that the gas is good. What do you mean by rebuilding the carbs?

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          • #6
            Re: No power

            One more note. We strongly doubt that it will rev up under load. It dies as soon as any throttle is advanced above the slight amount necessary to keep it running when lowering it into the water. It ran for about 5 minutes in this state, speed was slow idle, around 3 knots. Driver thinks he may have inadvertently advanced the throttle slightly when it stalled and would not restart. We pulled it and flushed it and are seeking advice.

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            • #7
              Re: No power

              Rebuilding the carbs means taking them apart and cleaning everyhting out, then replacing all the internal gaskets, diaphrams, check valves, o-rings, etc. You get one rebuild kit per carb, a new set of intake gaskets and some carb cleaner. We have a tech article taking you through it and videos on it.

              Engines always run fine up till the point of failure ;) If your brass gear striped on the rotary shaft, something either passed through the engine like debris or water - or you had a seizure for some reason.
              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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              • #8
                Re: No power

                Since you mention the engine turns in one direction but not the other, hard or won't start, chances the timing is off due to a stripped out brass sprocket on the rotary valve shaft. If you are going to pull the carb may as well pull the valve cover plate and check the timing. May see some damage in this area as well. Here's one I tackled the other day. Rider said it ran fine for an hour and then stalled and would not start again in or out of the water. Made for a horrific sound when trying to start. Cylinders and sleaves were also toast. Water injestion caused the failure.
                Attached Files

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                • #9
                  Re: No power

                  I need to clarify the sequence here. Carbs had been rebuilt by dealer prior to last summer (2005). This ski operates about 50 hours per summer.

                  Last fall, engine failed due to something sudden and significant. Dealer suggested replacing the engine which we did via SBT. We started the engine out of the water, it ran fine, so we winterized.

                  Earlier this week, we de-winterized. It started fine out of the water. We launched and it failed to start. We then picked up the rear of the hull and it started. It would immediately stall when lowered into the water. Finally, after several repeats of this, we tried keeping the throttle slightly higher and the operator was able to keep it running in the water at an idle pace for about 5 minutes. Then, it stalled again and would not restart. We towed, pulled, and it immediately started again with no load on the impeller.

                  We'll pull the carbs as suggested.

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