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  • lost top speed

    My 2001 GTI used to run around 40 - 45 MPH top speed. Blew engine last summer and had new SBT engine installed along with virtually every major engine part including impellor. Engine idles and accelerates fine. However, now it seems like it has no top end and max speed is around 30 MPH. Seems to just hum at full throttle and not wind out at max RPM. Only time the engine hits top rpm's is when boat comes out of the water. Mechanic has adjusted timing and carb to factory specs and engine is new. Help.

  • #2
    Re: lost top speed

    Check your compression (should be about 145) to rule out the engine. If multiple items were swapped, you have multiple items to rule out.

    Carbs should be set to 1 1/4 turns out low, 0 turns out high.

    Timing will not do that.

    Verify the impeller is the correct model, if it's overpitched it will do that.
    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: lost top speed

      Which impellor is correct? How can I tell?

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      • #4
        Re: lost top speed

        Some have a part number stamped on it, if it's an OEM part. If it's aftermarket all bets are of. Ordering the part through a dealer is the best way to know it's right. If it's not marked it takes an impeller shop like us to measure it and see what it is.
        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: lost top speed

          What are the steps to pull off the impeller. What is the correct pitch for the OEM impeller. I think the one I have now is a 21 pitch.

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          • #6
            Re: lost top speed

            Pitch numbers only compare to the same make and model, it's not a standard number. The OEM is what it is, there is no option for other pitches. If it's aftermarket, each model will have a few choices but it depends on which one it is, which pitch would be correct.

            How are you measuring, what brand and model impeller is it?
            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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            • #7
              Re: lost top speed

              Im not sure what brand. I'm only going by the invoice part no. 21-0262.

              Is it easy to take off?

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              • #8
                Re: lost top speed

                Whose invoice? It's not terribly difficult but they are on there pretty good.
                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


                • #9
                  Re: lost top speed

                  Local repair shop invoice. Probably no help.

                  I think its the impeller since everything else checks out and it won't make any power over 4500 rpms unless its out of the water.

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                  • #10
                    Re: lost top speed

                    Buy a new OEM from your Sea-Doo dealer.
                    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

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