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  1. #1
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    How is my ski even doing 66mph? Help

    Well here's my collection of pics, this was all installed by the previous owner. I got the ski a few months ago and now finally getting around to getting things right. Quite shocked it does 66 on the GPS I didn't run a compression test but it must be amazing to plow this through the water!

    I guess my question is after I remove all this stuff and clean it up, what specs should I start out with on measurements to get it correctly installed?

    Not sure what intake that is, but I ordered an R&D GP800. I also have to grind the pump to fit the ride plate (.980 raised in the rear?). I also have the parts needed to fix the broken bolt. What's up with the nozzle going up and down half an inch? Guess I need to washer that center too. The trim cable also has about half an inch of play up and down. Also I'm quite sure the square looking holes in the ride plate where it meets the hull should have silicone in them?

    Is the pump shoe low enough in the hull? Help me out here guys where do I start to get me up towards the 70mph mark.















    You can see the ride plate actually bumped out a bit from hitting the pump, I gotta flatten it back out.




    UP!


    Down!




  2. #2
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    Pump shoe has a solid nickel's gap on both sides.




  3. #3
    CJ's gpr's Avatar
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    What did yamaha claim from the factory like 64.5mph? That speed sounds about right but let's not forget that the skis almost 10 years old. my 03 does just about 62 now with no significant changes since 3 years ago when it ran 64. The only difference was 3 years of hard riding wearing out the old engine.

    We have pretty similar mods, I sold my EFI controller because my engine wasn't modified enough for it to make a difference. If you want to start pushing your engine you could look into doing some of the basic stuff like reed stuffers and sending your head out to get milled. I'm pretty sure Jim does this for a good price. Once you start really messing with the engine like this you'll definitely need an EFI controller.

  4. #4
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    Are the VF3 reeds still around for the non-pv motors like what's in my boat?

  5. #5
    Happily Self-Employed WFO's Avatar
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    VFIIIs are the same kit for 1200 pv and 1300 pv or non

    Not sure what intake that is, but I ordered an R&D GP800.
    That looks like a 1200/1300 grate. If you ordered one for a GP800, then you ordered the wrong one. A GP800R grate is faster on top end but no hole shot

    I also have to grind the pump to fit the ride plate (.980 raised in the rear?).
    Yes grind pump and nozzle. Thats not a Jims plate... looks like a Island Racing plate

    What's up with the nozzle going up and down half an inch? Guess I need to washer that center too. The trim cable also has about half an inch of play up and down.
    Check the trim cables at the pivot up front. They are probably loose

    Also I'm quite sure the square looking holes in the ride plate where it meets the hull should have silicone in them?
    No, dont seal there. Grind a bevel in the plate on both sides so the water wont catch there

    Is the pump shoe low enough in the hull? Help me out here guys where do I start to get me up towards the 70mph mark.
    If you have a nickel clearance there you are good

  6. #6
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    Who offers them forsale?

  7. #7
    Prism's Avatar
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    There are a few people that offer different reed setups. The most popular and best for all around recreational use imo are the VFIII's like you mentioned. The last set I puchased were from the last person that commented on this thread...WFO. His kit and reed spacer is of very high quality and includes o-ring seals seated in their own channel for leak free service. In the past gains of 100-150rpm on top have been seen with throttle response to match. These are a must if you want to go fast.
    His site is
    http://www.wfoperformance.net
    His email is
    [email protected]

  8. #8
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    Today? Got the R&D GP800r intake and filed that to fit in the hull perfectly. Man those come pretty rough took a while to get it sitting right.

    Measured the ride plate, it was currently at 1" rise in the rear. That explains why it was riding like a bucking bronco. Went to go add spacers.... low and behold one bolt was missing and the threads were all mucked...

    So this was my project tonight after work, replacing the metal thing in the hull that I picked up at the dealer... what a freaking nightmare to get at. It's drying in there with 5200 and tomorrow I'll get the ride plate shimmed to .750 and put the ski all back together. I bolted the plate in just to put pressure on it to hold it in for tonight.



    Tomorrow after it's all back together I'll get the plate specced right, put .030 spacers in the trim tabs, install Leo's wedge and the TTO tach. I stepped the sponsons too.

    I'll take it for a spin Friday after work and see what it does on the GPS. Hopefully better than my original baseline of 66 with everything all wacky.

  9. #9
    Prism's Avatar
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    Sounds like you're getting things sorted nicely! Remember to try and do things one at a time and test in between. Usual plate heights for top speed range from .950 to over 1". As you make more power it takes less plate angle to achieve the highest speed. This is why it's common to see a 72mph GPR with a 1.050 plate height but an 80+ mph GPR or conversion with a height of .950 or so. The fastest way to get the right angle is to set the height in your garage at .950. Then ride the ski and remove shims from the rear of the plate until the ski just starts bouncing on top. At that point stop with the ride plate shims and move to the trim tabs. Add washers under the tabs until the bounce goes away and the ride is solid on a smooth lake. Any time you increase power or add something like a pump wedge or prop this process needs to be repeated. I started modifying another GPR the end of last year for the girlfriend to use. I posted the process and results as I went if you want to see it in action. I will pick up the thread where I left off after the lakes thaw around here. I could have modded the crap out of it over the winter but refrained from doing so because I mod skis a certain way and wanted to document the results. I always bring a tuning notebook, tach, weather app and GPS. Hope this helps!
    http://www.greenhulk.net/forums/showthread.php?t=224741
    Last edited by Prism; 03-26-2015 at 07:49 AM.

  10. #10
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    Thanks!

    The ski came with everything but the GP800r intake and pump wedge when I bought it. When I got it initially it only had 70hrs and perfect compression (and looked brand new inside and out you should see the trailer it's beautiful even has swing tongue) but the owner's friend owned a shop and he would get "take offs" when a ski would come in without any knowledge of how to install. It was doing 63 when I first got it, had at least 5lb of silicone on the underside of the hull and some weird surface gap spark plugs that made it misfire (he was bragging how good those plugs worked). Well, put OEM plugs in, removed the silicone and that's where it sat at 66mph.

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