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  1. #1

    Join Date
    Mar 2006
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    363

    Lost 700rpm's for ever

    First of all I am Riva Service only Seadoo Tech and been in this industry for over fifteen years. It all started when i installed a Riva Stage II on my 2005 RXP.

    List of Mods: Riva High Flow Hood, Riva Intake Grate, Riva sponsons, Riva Air Intake, Riva IC, Riva Thru Hull, Riva Pro Block Offs, Riva Vortech impeller, Riva Pump Wedge, Les Clutch Washers, NGK Iridium Plugs, Ride Plate Holes Filled and Rotax Racing Stock Class ECU.

    First day after mods with a repitched Solas 14/19r I was at 74.8 mph but i was hitting the rev limiter. After hitting the rev limiter maybe thirty times, my revs started going down slowly till it reached 7400rpm's. Went home checked everything, then installed a new Solas15/20r, went out the next day and all i got out of it was 7600rpm's and 69.7mph.

    Went back and checked sc slippage 73 lbs/in, oil was perfect, wear ring was new and still new, impeller was perfectly pitched, compression is perfect, thru hull perfect, ic and tubes ith no leaks, air manifold ic plug completely sealed with silicone. So I installed stock ECU back and headed out again, it ran 7050rpm's, reinstalled Rotax Racing ECU and again back to 7600rpm's, changed to stock plugs and still the same.

    Went back checked fuel pump pressure which is perfect at 56psi, checked plug conditions and i am seen that it is running completely retarded. So i decided to change my wiring harness which i had removed the knock sensor piece in it and also install a new Rotax Racing ECU from a friend of mine. I will try it out tomorrow (Wednesday) and also will take a new mpem and a stock ECU just in case.

    But for now my RPM'S are lost for ever.


  2. #2
    Site Admin Green Hulk's Avatar
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    You hit the 8500 RPM rev limit 30 times with the stock valvetrain? Not good!

    I think with the RR Stock Class ECU you leave the knock sensor resistor in the wire harness. This could rob you of RPM's

    With the RR Race ECU you remove the knock sensor resistor.

  3. #3
    Site Admin Green Hulk's Avatar
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    Also, you will need to take 2mm pitch out of the trailing edge of that 15/20

  4. #4

    Join Date
    Mar 2006
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    Ok, but i tried the stock ECU with and without the knock sensor recall and still the same.

  5. #5
    Site Admin Green Hulk's Avatar
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    take 2mm out of your prop

  6. #6
    Quote Originally Posted by THE_PWC_GUY
    First of all I am Riva Service only Seadoo Tech and been in this industry for over fifteen years. It all started when i installed a Riva Stage II on my 2005 RXP.

    List of Mods: Riva High Flow Hood, Riva Intake Grate, Riva sponsons, Riva Air Intake, Riva IC, Riva Thru Hull, Riva Pro Block Offs, Riva Vortech impeller, Riva Pump Wedge, Les Clutch Washers, NGK Iridium Plugs, Ride Plate Holes Filled and Rotax Racing Stock Class ECU.

    First day after mods with a repitched Solas 14/19r I was at 74.8 mph but i was hitting the rev limiter. After hitting the rev limiter maybe thirty times, my revs started going down slowly till it reached 7400rpm's. Went home checked everything, then installed a new Solas15/20r, went out the next day and all i got out of it was 7600rpm's and 69.7mph. pump and look at the pick up tube.

    Went back and checked sc slippage 73 lbs/in, oil was perfect, wear ring was new and still new, impeller was perfectly pitched, compression is perfect, thru hull perfect, ic and tubes ith no leaks, air manifold ic plug completely sealed with silicone. So I installed stock ECU back and headed out again, it ran 7050rpm's, reinstalled Rotax Racing ECU and again back to 7600rpm's, changed to stock plugs and still the same.

    Went back checked fuel pump pressure which is perfect at 56psi, checked plug conditions and i am seen that it is running completely retarded. So i decided to change my wiring harness which i had removed the knock sensor piece in it and also install a new Rotax Racing ECU from a friend of mine. I will try it out tomorrow (Wednesday) and also will take a new mpem and a stock ECU just in case.

    But for now my RPM'S are lost for ever.
    almost sounds like my story word for word, I also put my stock ecu back and only got to 7400 rpm, I put my rr ecu in today and topped out at 8100 rpm. I rode my ski until it got to half a tank and then it just died almost like an electrical problem because it didnt sputter lkie it was running out of fuel, it just died quick. I was able to get it back to the trailer and I remeber that the last time I had this problem I was also at half a tank, I tried everything to get the boat to run I checked electrical connections, looked for leaks etc. when my motor quit I immediatly checked temp ( it was good) so after an hour and thinking about the half a tank I thought maybe it's the fuel pump or the pick up tube so I topped of the boat and it ran great. tomarrow I will have them test the pump and look at the p/u tube

  7. #7
    and let us know how the boat does after you put your buddies rr ecu in, curious to see if these rr ecu's are going bad

  8. #8

    Join Date
    Aug 2005
    Location
    Salinas CA
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    451
    Quote Originally Posted by skillet
    and let us know how the boat does after you put your buddies rr ecu in, curious to see if these rr ecu's are going bad
    My bone stock 05 RXP with 10 hour`s on it will not pass the 7400 RPM mark.

  9. #9

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    May 2006
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    my 06 hit 8100, takes a bit to get there.

  10. #10

    Join Date
    Mar 2006
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    I will post results tomorrow. "SKILLET" when testing your fuel pump you need to test it when key is plugged in, then engine on, and finally while riding. I have had alot of 06's that after riding for a while or when they get to half a tank the pump give out.

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