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  1. #1

    not getting the speeds i expected

    hey i have a 2005 rxp with:

    x-charger
    fizzle ic
    riva rear air intake
    thru hull exhaust
    131 degree riva thermostat
    rrpfr
    42 injectors
    solas 15/20r
    riva intake grate
    opas blockoffs

    i think thats everything.

    topped out at 74.9 today on the gps with slight chop. water temp 68 degrees and i think we are about sea-level haha, not sure.

    my main problem is porpoising, i cant seem to stay in the water at top speed even with minimal chop.

    second problem is i dont know how to setup my rrfpr...i have it set at 60 right now, should i raise it up a little?

    next thing is my rpms at WOT are about 8160-8169...slightly over the limiter..is that ok or am i losing speed?

    any help would be great. thank you


  2. #2

    Join Date
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    Quote Originally Posted by axl86 View Post
    hey i have a 2005 rxp with:

    x-charger
    fizzle ic
    riva rear air intake
    thru hull exhaust
    131 degree riva thermostat
    rrpfr
    42 injectors
    solas 15/20r
    riva intake grate
    opas blockoffs

    i think thats everything.

    topped out at 74.9 today on the gps with slight chop. water temp 68 degrees and i think we are about sea-level haha, not sure.

    my main problem is porpoising, i cant seem to stay in the water at top speed even with minimal chop.

    second problem is i dont know how to setup my rrfpr...i have it set at 60 right now, should i raise it up a little?

    next thing is my rpms at WOT are about 8160-8169...slightly over the limiter..is that ok or am i losing speed?

    any help would be great. thank you
    74 75 mph you need pro series blockoffs. i am having same problem with porposing on top end.

    your fuel psi?? do you have an a/f gauge, see if you are lean or rich.

    you want to be at 8100 you should increase pitch or try a smaller ring if you have a reduction nozzle.

  3. #3
    Golden Jet red fox's Avatar
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    Quote Originally Posted by busa504 View Post
    74 75 mph you need pro series blockoffs. i am having same problem with porposing on top end.

    your fuel psi?? do you have an a/f gauge, see if you are lean or rich.

    you want to be at 8100 you should increase pitch or try a smaller ring if you have a reduction nozzle.
    Where can i found the a/f gauge and how to install it ??

  4. #4

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    I wouldn't spend too much time worrying about the A/F ratio. If you have the 42's and base pressure at 60 (WOT pressure around 70), it won't affect your performance much.

    You could try shimming down the rear of the plate 0.020 to help with the porpoising.

    Other things to do are the wedge and fill the rideplate holes. Those mods are worth over 1 mph. Also, try tweaking the prop a touch, as mentioned.

  5. #5

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  6. #6
    Having Fun jp1300r's Avatar
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    Quote Originally Posted by red fox View Post
    Where can i found the a/f gauge and how to install it ??

    In the How-To-Section.

    AXL86 I think you are on the rev limiter. Maybe add some pitch and get revs down to 8100. I didn't know RIVA had 131* thermostat. I rode a 07 RXP to 81.4mph last weekend with stock OPAS in place. It did have a rideplate mod though.

  7. #7
    Quote Originally Posted by jp1300r View Post
    In the How-To-Section.

    AXL86 I think you are on the rev limiter. Maybe add some pitch and get revs down to 8100. I didn't know RIVA had 131* thermostat. I rode a 07 RXP to 81.4mph last weekend with stock OPAS in place. It did have a rideplate mod though.

    sorry its rotax racing 131 thermo. I want more rpms! i guess i gotta get an ecu then? Will it get slower if i go down to like 8100 rpm? repitch to like 15/22 sound about right?

  8. #8
    Moderator beerdart's Avatar
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    When you are on the limiter the ECU is pulling timing and power. Pitch the prop for 8100 and you will go as fast as your set-up will allow.

  9. #9

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    Quote Originally Posted by jp1300r View Post
    In the How-To-Section.

    AXL86 I think you are on the rev limiter. Maybe add some pitch and get revs down to 8100. I didn't know RIVA had 131* thermostat. I rode a 07 RXP to 81.4mph last weekend with stock OPAS in place. It did have a rideplate mod though.
    going to put 82 nozzel you need to ride again and see if we go faster.

  10. #10
    Having Fun jp1300r's Avatar
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    Quote Originally Posted by seadoolover View Post
    going to put 82 nozzel you need to ride again and see if we go faster.
    Okay thats it I am going to put the 81mm back in mine.

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