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  1. #1
    Site Admin Green Hulk's Avatar
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    77.0 MPH today - subtle changes i made to get there

    Most of you know that i ran a best speed of 74.6 at the Mudbug Nationals event while on the buzzer.

    The first thing i did was bolt up my new Riva grate. I was previously running the Worx grate. It is very important that you pay attention to the area where it fits next to the ride plate. You want this area to be flush, or true. I had to take a sander and grind off some area on the outside of the grate to make it fit flush with the rideplate as seen in this pic.



    As you can see i also fill the bolt hole areas of the grate with silicone. This not only fills the area of any voids, but also prevents the bolts from backing out.

    The next thing i did was fill in all the bolt holes on the rideplate. There are 6 of them on the RXP. I used a product called Bondo Glass and I got it from my local Autozone.




    I also bolted my 2 degree Riva wedge back up.

    My first run I was able to pull 75.9 with a full tank of fuel, but i was hitting the rev limiter at 8500 RPM's. I had my PPG 81mm speed venturi in my truck so I pulled the ski up and swapped the nozzles. This brought my RPM's down to 8400 with occasional flashes of 8450 and brought my speed up to 76.7.

    After burning off some fuel i managed to pull a 77.0 with 3 bars of fuel. I was porpoising at those speeds though. Stan has a rideplate mod i'm going to try that will get rid of the porpoising and bring the speed up. Can't wait to try it!

    Another thing worth noting is the air intake mod i did for the Mudbug Nationals. Basically i just used some 4" hose and attached it to the front of the Riva Power Filter tube and ran it to my filter element that I have mounted in my front top storage compartment. I also had the visor lid removed to help get some fresh cool air in. I don't plan on riding with it like this all the time. I'm waiting on the Riva high flow hood to become available and that should bring in all the fresh air that i need.






  2. #2
    If for some reason you ever have to, how dificult is it going to be to remove that bondo covering the bolt holes on your ride plate

  3. #3
    im glad you got to unlock some of your skis potental today. congrats on the speed
    mitch

  4. #4
    I trued the ride plate and grate on my old ultra 150 and never seen no speed increase. Are you sure you didnt gain speed with the new riva grate and wedge. Its kind of hard to believe this when you also added new parts.
    If the ride plate mod works are you going to give us the info on how to do that mod. That is one problem that I want to take care of on my rxp. I was hoping that riva was going to come out with something but you know it takes them forever on new parts.

  5. #5
    Site Admin Green Hulk's Avatar
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    Nah, i had the wedge on and off my ski many times in the past month. I think people report a .5 mph gain with the Riva grate over the Worx. My Worx was modified with the outer wings machined off so it was probably comparable to the Riva grate as far as speed. I went with the Riva grate for it's better hookup and handling properties. I also had my PPG nozzle on my ski for the Mudbug when i ran my 74.6.

    I gained 2.4 mph!
    I think the wedge/grate maybe gave me 1-1.5 mph. The rest came from filling the holes and truing the grate.

    If you look at the recessed areas on your rideplate for the bolts they are HUGE and cause lots of drag. It just makes sense to fill them in. The Fountain Racing boys know what they are talking about. Glad i took their advice! If i ever have to remove my rideplate i'll just have to get out the chisel to remove the filler. I'll cross that bridge when it comes.

    As far as instructions on filling the holes. Just mix the Bondo Glass up, slap it in the holes with a putty knife, spread smooth, let harden then sand it smooth.

    The other thing they said to do was take some 600 grit sandpaper and rub it a few times front to back on the hull. This is supposed to break the tension and is usually good for another mile per hour. I'll do it this week and have results by next weekend.

  6. #6
    Did you ever get around to actually having the hull trued? Getting rid of some of the hook would probably help things out. (less need for the wedge)

  7. #7
    mxl16's Avatar
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    excellent gains hulk. i am definatly going to give that a whirl. some really simple stuff and probably the most logical would give you that much of a gain. and not to mention pretty inexpensive aswell.

  8. #8
    Site Admin Green Hulk's Avatar
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    I haven't trued the hull yet. Mark Underwood and Nils Castillo will tell you in their experience that taking the hook out of the hull will cause porpoising. There is only one guy i know that has taken the hook out, but he has modded his rideplate to counteract the porpoising. It works very well. I may eventually do that rideplate mod and then take my hook out.

  9. #9

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    Ahhh, Jerry the Mad Scientists.
    Great news and wonderfull find jerry. That was a great find to help keep the bolts fomr backing out also. How hard is it to remove the "Bondo Glass" out of the holes if you ever need to remove the ride plate or grate?

  10. #10
    Site Admin Green Hulk's Avatar
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    The bondo glass in the ride plate bolt holes has nothing to do with the grate. The grate can be taken out very easily.

    "IF" you ever need to remove the rideplate just heat the bondo glass up slightly with a torch and then break out your trusty ole chisel and hammer and it will come right out.

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