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  1. #1

    85 mm nozzle causes the boat to bounce/buck

    Any body have trouble with this before? With the 87 nozzle and dual 3/8 PRV's it fine...

    With the 85 and duel 3/4 valves it bounces pretty violently above 80 mph. Sometimes it happens at 82 and once at 89...but it does it everytime you make a run and every time you let off the throttle after going 80 or more....

    I have a 92mm protec steering nozzle also....

    Any suggestions?


  2. #2
    Happily Self-Employed WFO's Avatar
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    which pump and grate?

  3. #3
    Sho pump with 15/22 and 800 ss grate.

  4. #4
    Happily Self-Employed WFO's Avatar
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    I had 2 different Rotax conversions that tried to stuff around 85mph or so with the 1200 grate and 85mm nozzles. We changed to the 87mm and they are good to over 90 now no problems. That 800 grate should not be stuffing with that set-up unless it or the shoe is not in there correctly.

    Did you drill the shoe also?

  5. #5
    Steve-m31164's Avatar
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    are the 2 x 3/8 reliefs enough ? I would not have thought so .. I went for more just incase .. I have no experience with using less reliefs .
    wait you say 3/8 then 3/4 ... what have you got ?

  6. #6
    Quote Originally Posted by Steve-m31164 View Post
    are the 2 x 3/8 reliefs enough ? I would not have thought so .. I went for more just incase .. I have no experience with using less reliefs .
    wait you say 3/8 then 3/4 ... what have you got ?
    Have option to run both...3/8 or 3/4

  7. #7
    Quote Originally Posted by WFO View Post
    I had 2 different Rotax conversions that tried to stuff around 85mph or so with the 1200 grate and 85mm nozzles. We changed to the 87mm and they are good to over 90 now no problems. That 800 grate should not be stuffing with that set-up unless it or the shoe is not in there correctly.

    Did you drill the shoe also?
    Shoe is not drilled...

  8. #8
    Happily Self-Employed WFO's Avatar
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    I pretty much drill the shoe on all the conversions now just to make sure no one goes flying off on decel.

    My 07 GPRSHO was 87mph with pretty much your setup, except 2 holes in shoe and was rock solid... stock wheel, garrett intercooler, R3, dynafly, HO pump, 85mm nozzle, ss800 grate, Jims FF, (2) 1/4" holes in shoe and (2) 3/4 valves with 1/2" hose

  9. #9
    Can the steering nozzle have an effect? I'm using a protec 92mm, it being that big I wouldn't think so but...

    Plate is at 930 and tabs 120 under all 4.

    I guess the 85 loads the pump more than the 3/4 valves can relieve...

  10. #10
    Steve-m31164's Avatar
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    it looks like there is a fine line and you are on the line . I have 2 x 6mm holes in the shoe also . 1 x 1" valve on 3/4 pipe and 2 x 3/4 valves on 1/2 hose . ss800 . R&D ff plate ,HO pump , tabs at 120.

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