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  1. #1

    Question Gp 1800 Pump Stuffing

    Hey all,
    Got a 2017 gp1800 had it on flat water for the first time since doing ride plate, intake and sponsons (I've never had the issue in the ocean even giving it all it has). Well it tried to throw me off around the 70mph mark (was still accelerating) which was a lot of fun. Sort of bounced 1 or 2 times (never unhooking) then bam! nose down hard and leaned to the left and slid/drifted 50 odd meters until the pump got back in the water and violently tried to eject me. I haven't heard of the gp's doing this so i'm assuming it was something i did.

    When i initially installed the intake grate (as instructed) i got really bad cavitation on hole shot so i removed it and sealed it 100%. Every edge of the intake grate is sealed to the hull and transom, it helped a little bit. Whilst i was at it i did the ride plate as well. So any water entering the intake has to go through the impeller and out the back. there is no way for the water pressure to bleed out anywhere else.

    Do you think this would be the culprit? i'm assuming it may be but will be a big job to fix so would love some thoughts on it.


    Mods below

    air intake
    ribbon delete
    worx exhaust
    13/18 solas
    worx intake with seal kit
    riva ride plate
    worx intercooler
    worx sponsons
    vtech stage 1 flash
    worx cooling kit

    Thanks


  2. #2
    Click avatar for tech links/info K447's Avatar
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    Check that the intake grate is physically centered and aligned with the hull centerline. It is possible to bolt up the intake grate with the grate front somewhat to the left or right compared with the rear of the grate, and relative to the hull centerline.

    Is the bottom rear of the intake grate flat/flush with the ride plate?

    Is the ride plate also centered/aligned and properly flush with the hull? Plate bolts tight, no air gaps between plate support bosses and hull along each side?

    Did you remove the transom plate and reseal that? If so, verify that the transom plate locating tabs are properly tight against the matching hull alignment bumps. And that the 155mm transom plate opening does match/align with the upper curve of the water inlet.

    Which sponsons? Tight to the hull, correctly installed, no damage?

    Is it possible you ran over some debris that momentarily snagged in the intake and caused the hull to act weird?

  3. #3
    Check that the intake grate is physically centered and aligned with the hull centerline. It is possible to bolt up the intake grate with the grate front somewhat to the left or right compared with the rear of the grate, and relative to the hull centerline.
    The grate is in nice and centered, with same I suppose gap around it to the hull (the wings on the intake grate are spot on square).



    Is the bottom rear of the intake grate flat/flush with the ride plate?
    Ride plate has a 1mm lip. the ride plate is lower than the intake grate.


    Is the ride plate also centered/aligned and properly flush with the hull? Plate bolts tight, no air gaps between plate support bosses and hull along each side?
    Just checked and yes bolts to spec, as far as I can tell its flush, I didn't use excessive amounts of sealant on the plate. The lines on the plate match evenly to the intake grate.

    Did you remove the transom plate and reseal that? If so, verify that the transom plate locating tabs are properly tight against the matching hull alignment bumps. And that the 155mm transom plate opening does match/align with the upper curve of the water inlet.
    No, I have not checked and re-sealed transom, I should have before installing everything. and yes the transom lines up with intake



    Which sponsons? Tight to the hull, correctly installed, no damage?
    Worx sponsons, fully down. No damage nice and tight.



    Is it possible you ran over some debris that momentarily snagged in the intake and caused the hull to act weird?
    No, I had a few weird feelings when in the ocean which makes sense now. So the last time I was out I was in slight cross chop just enough to move the ski about and it nosed in slightly. nothing crazy but it made me take notice. so then I found a area where it was almost glass and cautiously pushed it resulting in the above mentioned post. not sure on the speed as don't have gps speedo and the dream-o-meter is way off with the riva grate.



  4. #4
    fx160's Avatar
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    I know in the past sealing the front edge of the ride plate was a no no
    If you have sealed it
    That may be where the problem area is

  5. #5

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    You said above the ride plate was lower than the grate. The ride plate should be flush or a bit higher than the grate. Generally most do not seal the ride plate other than where the factory rubber seal is at.

  6. #6
    MSX 150 guy lives on Mr. GP1800's Avatar
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    I’d be looking at the sponsons. I really don’t think there is any way to mess up installing an intake grate and ride plate

  7. #7
    abracadabra's Avatar
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    I’m not saying anything because that’s a VERY difficult condition to correct.

    Here is my own personal experience:

    Scenario #1.
    2012 VXR heavily modded experiencing an Overstuffing condition. I drilled two 1/2” holes on the bottom of the intake grate (on the intake grate itself) and that corrected the condition.

    Scenario #2.
    2014 FX-SVHO heavily nodded experiencing an Overstuffing condition at right around 72MPH or above. The condition went away once I installed a ride plate cut by Jim’s Performance.

    Scenario #3.
    2008 FX-HO (1,100 motor) with just the RPM Kit. This is the only Year NanoXcell FX-HO 1,100 cc. Experiencing Overstuffing condition at 60 MPH. Worked on it for a while then I got rid of it before I could figure out what was causing the condition.

    Scenario #4.
    2006 FX-HO (1,100 motor). SMC hull Not NanoXcell.
    Exact same setup as above on 2008. Ran like a cadillac. No issues what so ever.

    ***All skis running on factory sponsons***
    ***All skis running perfectly fine on Salt Water or shoppy Waters***

    Ask Jerry about drilling holes on the intake grate prior to doing any work as he has done this mod and can tell you his experience before and after.


    ***I don’t need anyone to tell me “you should have done this or that or you’re crazy drilling holes on your intake grate***

    This is purely my personal experience.

    Hope this helps, Julio...

  8. #8
    MSX 150 guy lives on Mr. GP1800's Avatar
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    I would try taking the sponsons and raising them up. Aftermarket sponsons in their lowest position can really make for some aggressive handling.

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  10. #9

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    Hey man, totally agree with Mr gp, my mates did nearly the exact same thing last weekend, he shit himself, I was behind him and got it on GoPro. It behaved like my old VXR when it split the nozzle.
    we checked everything on his ski and it was mint. He's about 110 kilograms and had a full tank, at first I thought he had buttoned off for a wave and started to porpoise.
    sorry.....the point is, his ski is completely stock except for the sponsons, we raised them and went out again, once he finally got some balls back he gave it shit and all good.
    all the best

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  12. #10
    Thank for all the feed back, lots of good ideas,

    I'm goin to start by resetting the transom and whilst im at it have the mod done to it (Been wanting to do it anyway). Then make sure ride plate is level or higher than intake so there is no lip. And I will not be sealing the ride plate to the hull. If still no change ill give the sponsons a tweak and see if it does anything (Don't want to do too many changes at once).

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