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  1. #1
    kmaher's Avatar
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    New (to me) GPRSHO should be called GPRSLOW

    I've had the conversion bug for a while and was searching for a GPRSHO specifically. I didn't want a heavily modified one as it's going to be used for rec purposes only, and finally found one in NY I picked up a couple weeks ago.

    This weekend, I finally got a chance to take it out and water test it on some flat water, and I'm only running 71-72 mph.

    Now, there's a few things I noticed right away I can improve...sponsons aren't stepped, ride plate is too recessed and even with the shoe....but that's about it.

    I have a tach that should be arriving later this week so I can see what RPMs I'm truly turning, but the FZR dash indicates 7k even. My SVHO stock revs to 7,700RPM, and I was anticipating similar results with the SHO.

    It has the 160mm pump, stock SHO nozzle, and they said it has a stock pitch SHO impeller (but it's a SOLAS). Not sure what that is (13/20?)

    Surprisingly, holeshot is great, as is midrange, but 60-70mph takes forever.

    Straight out of the box, I was expecting 74-76mph. Engine is stock, but has ribbon delete, intake, and BOV.

    Am I right in thinking I'm way slower than I should be? Any suggestions on where to start with this thing?


  2. #2
    rxpredviper's Avatar
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    go with 155 pump and
    nice performace ride plate make a big different. or go with seadoo motor lol..

  3. #3
    kmaher's Avatar
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    I'm thinking the 155 pump would be a downgrade from the 160.

    It's got a RIVA machined plate on it right now....I'm thinking it's just not pitched right, but at a 13/20, I should be all over the limiter, not hitting 7000 max (unless that's a stock SHO motor RPM limit). Again, this is using the dash tach, so it could be off.

  4. #4

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    something is wrong, how is the supercharger clutch? With stock prop my gpsho hit 78mph on first test ride, sitting on the rev limiter. Sounds like it is down on power to struggle turning a 13/20

  5. #5
    kmaher's Avatar
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    Clutch seems to be fine - I don't notice any slipping, and the holeshot is surprisingly decent. It's not quite at the level of my GP1800, but not far behind, and from what I've seen written about GPRSHOs, that seems to be an anomoly.

    I'm thinking about sending it off to WFO seeing as he seems to have the tuning of these machines down to a science, and 83mph on a stock motor/ECU sounds pretty appealing. Only problem there is the transport from Ohio to Texas and back. I'd imagine that wouldn't be cheap. That said, I don't think I have any reputable tuning shops near me in Ohio. Closest would probably be Island Racing, but I don't know if Carl does a lot of work on the GPRSHO platform.

    My riding season is almost over, so I plan to dig into it and make improvements over the winter - both in performance and asthetics. Right now it's looking a little bit like Shamu and is in need of a makeover....

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  6. #6
    The first thing I would check is the health of the engine with a compression test. If that is fine I would look at is the engine possible hitting the limiter so hard it only turns 7K?
    Also the GPR has to be setup correctly to perform with plate angle, shoe alignment etc. With the hull setup properly and a bone stock engine with stock ecu 80 is very possible.
    78 with eyes closed. Something has to be wrong...boost leak, etc.

  7. #7
    The first thing I would check is the health of the engine with a compression test. If that is fine I would look at is the engine possible hitting the limiter so hard it only turns 7K?
    Also the GPR has to be setup correctly to perform with plate angle, shoe alignment etc. With the hull setup properly and a bone stock engine with stock ecu 80 is very possible.
    78 with eyes closed. Something has to be wrong...boost leak, etc.

  8. #8
    kmaher's Avatar
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    Compression seems good (120 across the board).

    Just received my PET Tach, so I plan to get out on the water this weekend and see what RPMs I'm actually turning.

    The hull set up isn't so great right now, but I'm going to tweak few things before hitting the water and see what sort of results I get.

    The hull overall is in good shape, but there were a number of things not functioning properly when I picked it up. I just got trim working again, which should hopefully help me out, although it was stuck with the nose all the way up, so I was probably already maximizing speed. I'll adjust sponsons and rideplate before I go out and see what I'm able to get.

    The strangest thing is that pull from 60 - 70. It picks up speed with ferocity until then, but at 60 it just become a gradual climb. I kind of figured these are supposed to accelerate with tenacity all the way to the rev limit.

  9. #9
    Steve-m31164's Avatar
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    They do 70plus mph with a na motor . I would be looking at a boost leak or at the clutch ..

  10. #10
    kmaher's Avatar
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    Got a little more saddle time in this weekend, and I'm starting to lean a little towards the clutch being the culprit.

    My experience with Yamaha clutches have always been either "on" or "off" when they go bad, whereas it feels like maybe this one has a little give, and then bites, etc. The slipping is subtle, though.

    Good news is I already had one of the Dean's Team clutches on order, so hopefully that solves most of my issues. I'm still thinking I'm going to send it to WFO for the winter to get it in perfect working order.

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