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  1. #1

    Join Date
    Jul 2008
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    ocala florida
    Posts
    62

    gprxp prop ?? need some help

    i know im beating a dead horse but need little advice
    02 gp1200
    04 rxp motor stock ecu x blowe only mods
    ho pump 14//20 solas df

    gps 78mph @8100


    problem is it hits good right off bottom end, just before it gets on plane cavitates really bad have to feather thottle then it will finally go and its good to go after that

    before i had a 15//21 repitched scat track with a 160mm wear ring and it was opposite
    cavitated really bad off bottom end then was fine after that


    trying to get all the kinks worked out before i add some power to the ski

    modded ride plate at about a 5 degree upward angle pretty sure 87mm nozzle and a riva aluminum steering nozzle fixed to a 5 degree upward angle

    i have to get my trim setup on it before i can swap outlet nozzles as someone has rigged the sterring nozzle angle before me i just changed the threaded rod to make different angles


    would like to get the ski around 80 81 before i add some power

    hope someone has some advice for me as im stumped right now

  2. #2

    Join Date
    May 2012
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    California
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    Quote Originally Posted by dabeetereater View Post
    i know im beating a dead horse but need little advice
    02 gp1200
    04 rxp motor stock ecu x blowe only mods
    ho pump 14//20 solas df

    gps 78mph @8100


    problem is it hits good right off bottom end, just before it gets on plane cavitates really bad have to feather thottle then it will finally go and its good to go after that

    before i had a 15//21 repitched scat track with a 160mm wear ring and it was opposite
    cavitated really bad off bottom end then was fine after that


    trying to get all the kinks worked out before i add some power to the ski

    modded ride plate at about a 5 degree upward angle pretty sure 87mm nozzle and a riva aluminum steering nozzle fixed to a 5 degree upward angle

    i have to get my trim setup on it before i can swap outlet nozzles as someone has rigged the sterring nozzle angle before me i just changed the threaded rod to make different angles


    would like to get the ski around 80 81 before i add some power

    hope someone has some advice for me as im stumped right now
    that prop cavitates out of the hole, if you spin it up faster you will get your speed. you either build for top speed or you build for holeshot, cant really have both.

  3. #3

    Join Date
    Jul 2008
    Location
    ocala florida
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    62
    Quote Originally Posted by toxicgun View Post
    that prop cavitates out of the hole, if you spin it up faster you will get your speed. you either build for top speed or you build for holeshot, cant really have both.
    Ski did not do this before with a old inefficient scat track the old prop I could feather it and it be fine, this one does not do this like it's just sucking air period not water hard to explain through words gonna try and get a video of it soon

  4. #4

    Join Date
    Mar 2012
    Location
    North, NJ
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    i have the same problem, cavities like CRAZY off the bottom but if im causing at 3k and punch it, she takes off like a rocket.. only thing is im not sure what prop i have, as i bought it this way...

  5. #5
    Kmorningstar_rxp's Avatar
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    Feb 2015
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    Port orange, Fla
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    1,672
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    Quote Originally Posted by Wakeboardcraze View Post
    i have the same problem, cavities like CRAZY off the bottom but if im causing at 3k and punch it, she takes off like a rocket.. only thing is im not sure what prop i have, as i bought it this way...
    Thats normal... can’t have a ski like this that hole shots lol.. these are either built high speed or hole shot like toxic said... mine wouldn’t move until I was moving along and then pinned it... the df like rpm.. turn it up and she’ll make the speed

  6. #6
    rxpredviper's Avatar
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    WPB
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    Quote Originally Posted by dabeetereater View Post
    i know im beating a dead horse but need little advice
    02 gp1200
    04 rxp motor stock ecu x blowe only mods
    ho pump 14//20 solas df

    gps 78mph @8100


    problem is it hits good right off bottom end, just before it gets on plane cavitates really bad have to feather thottle then it will finally go and its good to go after that

    before i had a 15//21 repitched scat track with a 160mm wear ring and it was opposite
    cavitated really bad off bottom end then was fine after that


    trying to get all the kinks worked out before i add some power to the ski

    modded ride plate at about a 5 degree upward angle pretty sure 87mm nozzle and a riva aluminum steering nozzle fixed to a 5 degree upward angle

    i have to get my trim setup on it before i can swap outlet nozzles as someone has rigged the sterring nozzle angle before me i just changed the threaded rod to make different angles


    would like to get the ski around 80 81 before i add some power

    hope someone has some advice for me as im stumped right now
    go for top speed is fun , hole shots not good .

  7. +1 by:


  8. #7

    Join Date
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    Now I am running a 14/25 and basically just got used to the idea of limited holeshot. I make it up with midrange and top end, always a trade off.

  9. +1 by:


  10. #8

    Join Date
    Mar 2012
    Location
    North, NJ
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    think im going to go for the sea-doo pump conversion found a pump for cheap on facebook marketplace, or just end up selling and buying a gp1800... there so fun and holeshot is amazing, allthough im still faster than all the ones I've raced

  11. #9
    Steve-m31164's Avatar
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    Jan 2013
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    Melbourne Australia
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    With my gprxp i have a few pump setups now , i have a trusty HO pump with a boat prop , it cavitates like a pig but at 30mph it pulls like a train . And a sho pump with a 17/27 skat that is similar but faster with less revs , i have a SS 800 grate , the 1200 grate has less cavitation. You cant have both unless you get a twin prop setup with a seadoo or a sho/svho pump setup , and then you are still limited by the grate
    Last edited by Steve-m31164; 01-03-2019 at 02:24 PM.

  12. #10
    Quote Originally Posted by dabeetereater View Post
    i know im beating a dead horse but need little advice
    02 gp1200
    04 rxp motor stock ecu x blowe only mods
    ho pump 14//20 solas df

    gps 78mph @8100


    problem is it hits good right off bottom end, just before it gets on plane cavitates really bad have to feather thottle then it will finally go and its good to go after that

    before i had a 15//21 repitched scat track with a 160mm wear ring and it was opposite
    cavitated really bad off bottom end then was fine after that


    trying to get all the kinks worked out before i add some power to the ski

    modded ride plate at about a 5 degree upward angle pretty sure 87mm nozzle and a riva aluminum steering nozzle fixed to a 5 degree upward angle

    i have to get my trim setup on it before i can swap outlet nozzles as someone has rigged the sterring nozzle angle before me i just changed the threaded rod to make different angles


    would like to get the ski around 80 81 before i add some power

    hope someone has some advice for me as im stumped right now

    you are cavitating because the pump is un loading then reloading as you get up to speed the stuff will go away but may come back. have you changed the nozzle to a smaller size say 83 or 85.Have you done anything to the pump shoe angle at which the water enters the pump. there is a hump on both sides of the shoe that you can massage a little so the water hits the prop almost dead center again and instead of one blade or two processing the water you now have all the blades doing there job.

    when the ski stuffs at high speed it is due to the angle of the pump shoe.The water hits the humps in the pump shoe and makes the water angle towards the top of the prop there for going from 4 blades to say two or perhaps one and the pump can not process the water. you want the water entering the pump tunnel to hit the prop dead center so the pump can process all of the incoming water.


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