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  1. #1

    Canít get ski to stop bucking at high speed. Dangerous

    21 GP 1800 SVHO stage 4 here. Ski used to get to 70 mph and then buck on the water. This was with the riva gen 2 ride plate and intake grate. Wound up actually loosening the seal between the intake grate and ride plate. It was almost ready to fall out of the back of the ski. I took the ride plate off and put my stock cut plate on and sealed everything and it seemed that the problem went away.

    Today I was doing a pull and at about 90-91 mph the ski started bucking so bad it almost threw me off as it started to turn towards the shore whereís there rocks and trees. The ski was bouncing on the water like you would skip a rock, when I let off the throttle it still took a second to slow down and I was hanging off the ski with my left arm still holding the bar and that was about it.

    I jumped in the water and felt for anything missing or out of place and everything was fine. On the way back to the dock I slowly accelerated up to 85 ish and as soon as it hit 87 the ski lost all its planing and nose dived into the water. I tried to hang on(sitting down this time) and stay on the throttle and it was like riding a bull at a bar like a drunken girl.

    When I got home I went under the ski and all looks normal, seal is in place and so is all the silicone I used to seal everything. I cannot ride the ski this way it scares the hell out of me. Had I been just 5 feet farther to the right it wouldíve been a bad crash.

    Itís something related to the intake grate/ride plate and I canít figure it out. The riva gen 2 intake grate fits like absolute crap on the 21 compared to the stock one but Iím not sure how that could possibly cause this. Iíd like to just put the stock one on as there was almost no performance benefit from the riva minus it being steel, everyone is so dead set on the stock one breaking over 80.

    I personally loved the riva gen 2 ride plate as it didnít bounce when cruising with a passenger at 60 like the stock plate does or when youíre low on fuel. I canít see myself putting it back on after what Iíve been through with this thing. The only constant is this intake grate and I donít know what else to use for the 21.


    I have had such terrible luck with 75% of the stuff I bought from riva. Not sure if itís my luck or the fact that I have a 21 but this is the second intake grate they had to give me as the first one wouldnít fit no matter how much you grind on it. The 100lb injectors were so poorly flowing that my ski wouldíve probably blown up on the first few pulls. Luckily I have an injector cleaner and flow tested them before I put them in. Iíve learned my lesson from other injectors Iíve bought. The intake hit the gas tank on the 21 since they moved it farther back so would up returning that for a Fizzle intake.


    hopefully someone has had this issue and can help me fix it.

    thanks in advance!


  2. #2
    raiderx72's Avatar
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    Make sure seal is properly fitted. And your using correct bolts for ride plate and intake grate sometimes they get mixed up and ride plate appears to be tight but isnt.

  3. #3
    Quote Originally Posted by raiderx72 View Post
    Make sure seal is properly fitted. And your using correct bolts for ride plate and intake grate sometimes they get mixed up and ride plate appears to be tight but isnt.
    Everything is tight and they are the correct bolts. Everything is sealed up nice and tight. Well, I took the ride plate off but the seal was in tact and so is the seal on the intake.

  4. #4
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by NicksPerformance View Post
    Everything is tight and they are the correct bolts.

    Everything is sealed up nice and tight. Well, I took the ride plate off but the seal was intact and so is the seal on the intake.
    There are two seals. The flat OEM rubber Ďfingerí strip and the pump seal kit for the Riva intake grate.
    You have both installed, correct?

    Do you apply sealant around the back face/rim of the intake grate where it mates to the curve of the transom plate?

    Can you confirm that none of the intake grate bolts have stripped the threads in the hullís aluminum inserts?

    There are no hairline cracks anywhere around the intake grate mounting bolt locations?

    Does the bottom of the ride plate align with the bottom of the intake grate?
    Both are in the same plane, with just a thin gap where the OEM rubber seal is visible and correctly positioned.

  5. #5
    raiderx72's Avatar
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    Also you dont have the "launch" auto trim on do you?

  6. #6
    Quote Originally Posted by K447 View Post
    There are two seals. The flat OEM rubber ‘finger’ strip and the pump seal kit for the Riva intake grate.
    You have both installed, correct?

    Do you apply sealant around the back face/rim of the intake grate where it mates to the curve of the transom plate?

    Can you confirm that none of the intake grate bolts have stripped the threads in the hull’s aluminum inserts?

    There are no hairline cracks anywhere around the intake grate mounting bolt locations?

    Does the bottom of the ride plate align with the bottom of the intake grate?
    Both are in the same plane, with just a thin gap where the OEM rubber seal is visible and correctly positioned.
    I’m under the ski now with everything removed. Nothing is stripped. The Riva seal kit and the flat seal were both where they needed to be. The intake grate was even with the ride plate and I siliconed over the small gap between them. No cracks or anything, just finished removing the old silicone.

  7. #7
    Quote Originally Posted by raiderx72 View Post
    Also you dont have the "launch" auto trim on do you?
    Auto trim on or off doesn’t matter. It still did it. On the way to the dock I turned it off and it did it at 88 trim all the way up.

  8. #8
    raiderx72's Avatar
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    Auto trim will do it.. especially at those speeds.

  9. #9
    Quote Originally Posted by raiderx72 View Post
    Auto trim will do it.. especially at those speeds.
    I generally have it off when I’m doing pulls so I can control the trim myself but it did it both ways.

  10. #10
    Seems like what’s happening here is pump stuffing... JP racing just got off the phone with me and explained it. Only thing I can do is go back to a stock intake grate...

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