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  1. #1
    PETRUS's Avatar
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    Good RPMs / Bad MPHs

    I d like to ask advice to find out why i have lost 2mph at same rpm over the last few months

    My set-up is 07 RXP (170 hrs), 8.600 ECU reflash, ET140 charger, 50" injs, Riva rrfpr @59psi, 4" front air, XS IC with HKS BOV, Riva open loop kit, Riva grate & 255 plate, 83 ring, 15/20R untouched

    Air & water 90F then and now

    I used to gps +79mph @8.400 rpms (best 79.5), now i can only get +77mph @8.400 rpms

    I tested with 82 ring and it got worse: rpms were down only 50 to 8.350, but speed went down to +75mph

    I would understand the speed loss if rpms were down on par but they stay solid...

    Carbon seal, wear-ring & pump-shoe were all replaced less than 10hrs ago.
    Compression check showed 130 across the 3 cylinders.

    What do i do now?
    Thanks!


  2. #2
    speedskixp's Avatar
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    Quote Originally Posted by PETRUS View Post
    I d like to ask advice to find out why i have lost 2mph at same rpm over the last few months

    My set-up is 07 RXP (170 hrs), 8.600 ECU reflash, ET140 charger, 50" injs, Riva rrfpr @59psi, 4" front air, XS IC with HKS BOV, Riva open loop kit, Riva grate & 255 plate, 83 ring, 15/20R untouched

    Air & water 90F then and now

    I used to gps +79mph @8.400 rpms (best 79.5), now i can only get +77mph @8.400 rpms

    I tested with 82 ring and it got worse: rpms were down only 50 to 8.350, but speed went down to +75mph

    I would understand the speed loss if rpms were down on par but they stay solid...

    Carbon seal, wear-ring & pump-shoe were all replaced less than 10hrs ago.
    Compression check showed 130 across the 3 cylinders.

    What do i do now?
    Thanks!
    Have you seen good speed since the pump shoe replacement?

  3. #3
    PETRUS's Avatar
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    Quote Originally Posted by speedskixp View Post
    Have you seen good speed since the pump shoe replacement?
    Yes, the speed seemed ok after new pump shoe

  4. #4
    Site Admin Green Hulk's Avatar
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    Quote Originally Posted by PETRUS View Post
    Yes, the speed seemed ok after new pump shoe
    Tony, it Seemed okay after the pump shoe replacement or ran 79+ mph after the pump shoe replacement?

    If the ski hasn't run 79 mph since the pump shoe replacement then I think your problem lies there.

    Have you checked the clearance between the wear ring and impeller?

  5. #5
    PETRUS's Avatar
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    Quote Originally Posted by Green Hulk View Post
    Tony, it Seemed okay after the pump shoe replacement or ran 79+ mph after the pump shoe replacement?

    If the ski hasn't run 79 mph since the pump shoe replacement then I think your problem lies there.

    Have you checked the clearance between the wear ring and impeller?
    Hi Jerry, it ran 79+ after pump shoe replacement, problem appeared some time after

    Ring/prop clearance seems ok when looking into the pump with a flash-light,
    the wear-ring is new...
    do you recommend i pull the pump for inspection?

    When the dealer changed the shoe, i asked them to align engine too, they wouldn't have bothered checking it if i didnt mention ... i remember they put 2 shims under each rear mount, that seemed a lot...

    If it was a boost leak, rpms would be down too, correct?
    so we can narrow it down to a pump or alignment problem?
    Thanks

  6. #6
    PETRUS's Avatar
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    I did notice something unusual after dealer replaced pump shoe/ wear ring /carbon seal,
    after the first ride i found this black carbon line all around the inside of the hull at the level of the seal, see pic attached.
    It s everywhere, at the bottom of the hull, on the sides, even on the inside of the seat.
    At first it was a very thin fine line like laser-etched, now it s thicker & blurred, i havent cleaned it so i could show it to them next time.
    Is this a sign of bad alignment?
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  7. #7
    Eric Ocman's Avatar
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    Quote Originally Posted by PETRUS View Post
    I did notice something unusual after dealer replaced pump shoe/ wear ring /carbon seal,
    after the first ride i found this black carbon line all around the inside of the hull at the level of the seal, see pic attached.
    It s everywhere, at the bottom of the hull, on the sides, even on the inside of the seat.
    At first it was a very thin fine line like laser-etched, now it s thicker & blurred, i havent cleaned it so i could show it to them next time.
    Is this a sign of bad alignment?
    When I replaced my carbon seal a few months back mine did the same thing inside the hull. I suspect just because its new. Some people have said that means the seal is bad but I have no issues bro.

  8. #8
    Mod less, ride more! troyheb's Avatar
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    Quote Originally Posted by PETRUS View Post
    I did notice something unusual after dealer replaced pump shoe/ wear ring /carbon seal,
    after the first ride i found this black carbon line all around the inside of the hull at the level of the seal, see pic attached.
    It s everywhere, at the bottom of the hull, on the sides, even on the inside of the seat.
    At first it was a very thin fine line like laser-etched, now it s thicker & blurred, i havent cleaned it so i could show it to them next time.
    Is this a sign of bad alignment?
    Like Eric said, some do that when they are new.

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