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  1. #1

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    2018 FX SVHO a little squirly at 74 mph

    So this year a added a MaptunerX stock tune and a Riva intake grate. Also sealed the pump and new grate. I donít know if itís the additional 5-6 mph or the new Riva intake grate but at top speed (74-75 mph) it seems to be a bit floaty and kind of gently and ever so slightly wanders. I probably would never think twice about it at slower speeds (My old Wave Raider was a handful at times) but at 74+ mph Iím a little concerned that I may have an issue that needs to be addressed before I make any more mods, add any more speed or someone gets hurt. I canít accurately put it into words but Iím hoping some of you guys might have an idea of what Iím talking about.
    Thanks
    Bill


  2. #2
    Click avatar for tech links/info K447's Avatar
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    My understanding is that the generation of FX hulls that I think includes your model year FX was known to have squirrelly handling at speeds much above stock.

    Riva has a ride plate * that in part was designed to correct the unacceptable handling with the stock ride plate.

    Somewhere on here are several threads with more details regarding the need for a fix for the stock FX hull handling when aftermarket/tuned speeds are happening.

    * I do not recall whether the Riva fix was a combo of ride plate and intake grate.

  3. #3

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    Yeah, I was thinking the same thing. When I searched all I found was threads talking about the 2019 hulls and up. I wasn’t able to find any threads on the 2018 generation of FX hulls. I’m sure my phrasing in the search criteria has something to do with that since I seem to always have a problem with that.

  4. #4

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    I wonder if I search for threads with the Riva ride plate or Jims modded plate might help.

  5. #5
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by Fandini View Post
    Ö threads talking about the 2019 hulls and up.

    I wasnít able to find any threads on the 2018 generation of FX hulls. ...
    I may have been incorrect in thinking of 2018 being the year when Yamaha revised the FX hull using a derivation of the GP1800 hull. It may well be 2019 when the hull design was changed.

    If so, my apologies.

  6. #6

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    Quote Originally Posted by K447 View Post
    I may have been incorrect in thinking of 2018 being the year when Yamaha revised the FX hull using a derivation of the GP1800 hull. It may well be 2019 when the hull design was changed.

    If so, my apologies.
    No problem. Might be why I can’t find anything when searching. Maybe my explanation is a little off. Just doesn’t seam securely planted and sucked down hard to the water in the tail end.

  7. #7
    Hurricane1000's Avatar
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    Is it on the edge of stuffing the pump?

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    Quote Originally Posted by Hurricane1000 View Post
    Is it on the edge of stuffing the pump?
    WOW! I hadn’t thought of that. I guess it could be. I’m turning about 8200 RPM’s on a Rive 8300 RPM stock tune. Talked to Riva tech support today about target RPM’s and wondering if I should try to bring em down a hundred RPM’s do so. They said they would keep nothings as they are. What can I do to alleviate stuffing the pump if that’s the case and how do I make sure that’s what is going on?

  9. #9
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by Fandini View Post
    Ö Iím turning about 8200 RPMís on a Riva 8300 RPM stock tune.

    Talked to Riva tech support today about target RPMís and wondering if I should try to bring em down a hundred RPMís do so. They said they would keep nothings as they are.

    What can I do to alleviate stuffing the pump if thatís the case and how do I make sure thatís what is going on?
    Your running RPM are very close to the tuneís fixed limit.

    As as test, try raising the tune RPM limit by 200-300 RPM. See if the weird handling at top speed changes.

    I am somehow suspecting that you are actually touching the RPM limit at WOT and the tune PRM limit activation is causing engine power to vary, cycling down and back up, and that power variation is causing at least some of the handling symptom you are experiencing.

    Raising the tune RPM limit will not increase the running-on-the-water peak RPM unless the current tune has been suppressing the engine at WOT.

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  11. #10

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    Quote Originally Posted by K447 View Post
    Your running RPM are very close to the tune’s fixed limit.

    As as test, try raising the tune RPM limit by 200-300 RPM. See if the weird handling at top speed changes.

    I am somehow suspecting that you are actually touching the RPM limit at WOT and the tune PRM limit activation is causing engine power to vary, cycling down and back up, and that power variation is causing at least some of the handling symptom you are experiencing.

    Raising the tune RPM limit will not increase the running-on-the-water peak RPM unless the current tune has been suppressing the engine at WOT.
    Great idea. Riva tech support recommended that I use the MaptunerX to monitor my RPM’s using the diagnostic port to actually see how my RPM’s are doing and how close they are to having the computer start to detune the engine to avoid hitting the rev limiter. I was actually wondering if I was bumping the limiter in some fashion but both the overstuffing and backing down the RPM’s could be the issue. HMMMMM

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