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  1. #1

    Adjust-A-Thrust right for me?

    I own a 2006 15F with the FULL Riva RPM Kit. All my riding is done on the Mississippi River or some local lakes. I don't encounter much chop but when I do it's about 3 foot max, obviously I don't try to do a high speed run when it's like that. Anyway, my current high GPS speed is 67.6mph. I'm pretty sure in perfect conditions I can hit 68mph, but my overall goal is a 70mph 15F.

    Now my question is this. Would my 15F benefit from an Adjust-a-Thrust kit? I did a search and found a couple old threads about the unit but really no results or in-depth opinions about it. Is there anyone out there that has this along with the RPM kit on their 15F? If so I would love to hear what you think about and what you gained/lost speed wise once you installed it.

    Thanks in advance.


  2. #2
    AaronC's Avatar
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    I have some input about this mod but I need to take some pictures of it to make any sense of it.

  3. #3
    hello ive got the whole riva rpm kit on and i fitted the adjust a thrust to the pump
    ive not had a right chance to dial it in yet but i have the small cone on and when I ran it at our local harbour (we can do what we like in it )
    i ran 61.8mph the speed before the A.D.T. was 60.7mph
    the distance i ran was about 300 yards approx will test the other cones when the water is calm enough
    but the good news now is that my 15f can keep up with a new 2007 RXT
    i had a 9 mile straight line race down a flat river with my mate and we were neck and neck all the way
    but when we are out at sea in the chop the RXT pulls away

  4. #4
    AaronC's Avatar
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    Here are some pics of it with no shutte, short shuttle, and longest shuttle. I have pics of both shuttles retracted and at full length to show the range in which they grow. Note how much bigger the body of the AAT is in comparison to the stock tail cone. Also note where the stock tailcone would sit flush against the pump and it makes the difference a little bigger.

    This being said, the AAT takes up A LOT more space in the pump than the stock cone. Based on the theory of the AAT, it should allow more holeshot than the stock cone because the shuttle is retracted and (supposed to) allow more space in the pump. In reality it's much bigger so in theory this can't happen. In theory, when the shuttle is fully extended it should raise pump pressure and thrust. My experience is that it limits the amount of water the pump could let out and cost me speed with a shuttle on a stock nozzle outlet. Now the instructions do clearly state that this mod works best with an impeller pitched on the higher side. An after maket impeller works wonders on this ski so I ditched the stocker but perhaps this was one reason for my bad results so far. So I bored the nozzle 2mm to unstuff the pump and allow more water out. This did work, and helped as I could put in a short shuttle and not lose speed anymore. Now I'm having my Solas impeller tweaked to give more Rev's and attempt to dial the rest in with the AAT.

    I have not given up on the unit. I believe the theory is good, the product is made of high quality and that I can make it work as designed. I will have it all back together here in a week and do a lot more testing with my Solas prop pitched to pull 7800.
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  5. #5
    Thanks AaronC. Just let me know what your results are after you get your ski all put back together and running.

    Thanks again.

  6. #6
    Tube Master's Avatar
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    To AaronC, if you remember my post on mod's on my two ski's......
    I have the RIVA RPM kit with some X-Tra air holes and so on. Any way FYI I'm running A Solas 14-21 with A 2* wedge. Just for the hell of it I took the wedge out and put stock prop on, pitched to 12-20 by Impros. I lost A solid 5mph on GPS I have one AAT sitting in box just waiting to see if some one gets the right combo

  7. #7
    Dubz1's Avatar
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    I lost 5 mph with the worx intake. It keeps me hooked, but I now ride slow as hell. I was hit 62.9 mph, now I cant seem to get past 58 mph. I'm changing back to my stock intake soon, and see what happens..

  8. #8
    AaronC's Avatar
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    Quote Originally Posted by Dubz1 View Post
    I lost 5 mph with the worx intake. It keeps me hooked, but I now ride slow as hell. I was hit 62.9 mph, now I cant seem to get past 58 mph. I'm changing back to my stock intake soon, and see what happens..

    I could barely crack 62 mph with my grate on. I took it off too

  9. #9
    AaronC's Avatar
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    Quote Originally Posted by Tube Master View Post
    To AaronC, if you remember my post on mod's on my two ski's......
    I have the RIVA RPM kit with some X-Tra air holes and so on. Any way FYI I'm running A Solas 14-21 with A 2* wedge. Just for the hell of it I took the wedge out and put stock prop on, pitched to 12-20 by Impros. I lost A solid 5mph on GPS I have one AAT sitting in box just waiting to see if some one gets the right combo
    I'll let you know how my setup turns out. Jerry said it should get the extra 200-250 rpms i'm looking for. I don't have an accurate tach but most days I would get 4 bars on the factory tach which would put me just over 7600 rpm. But on some days I could only pull 3 which leads me to believe I'm somewhere between the high side of 3 and lowside of 4 bars. Now I should be on the high side of 4 and flicker 5 and be in the 7800-7850 range. Hopefully this will pick up some speed as it works with the RXP's he does. Someone else recently tried this on his 15f and said he went from 66 to 69 so I had to find out what the dealio was. I'll have the ski on the water mid next week and some early morning good flat water to GPS in. I'll be trying no shuttle, to every shuttle in the bag and give a report as to what I find. My impeller was bent 2mm the last 1 inch of the trailing edge.

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