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  1. #1

    Finally got to ride my 05 Rxp and have some questions.

    Ordered my Rxp in February, finally came in in April, took 5 weeks to get my parts back from Canada, which turned out very nicely, just wrapped things up today. Took it reasonably easy on the motor tonite. At 1.5 hours of run time and 25 miles on the boat, gas gauge still read full bars, from 45 mph nailed the throttle for about 8 seconds. Gps'd @ 73.5 @ 8100 rpm trim in nuetral position. 85 degree ambient and 77 degree water temps, light chop. Ski comes out of the hole as least hard as my heavily modded 97GP1200 with a Skat 12 vein magnum pump then pulls very hard through midrange. There is absolutely no prop spin or cavitation. Motor is extremely smooth in all rpm ranges. I'm sure the ski will run faster when I can hold it wide open and when gas runs low. I'm thinking the prop may be overpitched but I'm hesitant to touch it due to the performance out of the hole and in accelleration. Impros bent a stock concord 14/19 to 14/20, which is what I am running currently. I have a Rotax stage 3 kit, exhaust manifold porting, water box mod, 4" air intake, Riva intake grate, Riva sponsons, no pump wedge and still running OPAS until Riva ships me the perfomance Opas removal kit, which should arrive this week. Will be adding the high flow hood also, which should arrive shortly too. Is the ski performing as should be expected?
    At 30 miles the gas gauge dropped one bar. How many gallons of gas does each bar equate to? Seems to be getting very good gas mileage.
    Thanks for the input.


  2. #2
    Site Admin MikeTrin's Avatar
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    Welcome Mark, you scared me with your post, I thought you had a 73 mph stock ski .. lol. Then I read the mods, nice!

    The gas gauge is a pain, it'll sit around full for a while, then just drop like a dead horse. I don't pay any attention to how much i burn. I just keep filling it.


  3. #3
    Site Admin Green Hulk's Avatar
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    Mark, i have the Stage 3 kit as well and your speeds are in line with what im seeing allthough i may be a little faster, but you aren't even broken in yet. I think my speeds are very low with this kit considering that back in the winter time i was able to pull 76 mph without the ported head and cam. I guess heat plays a huge role in the performance of these things though.

    By the way, your RPM's are a bit low. Optimum should be 8350-8400

  4. #4
    Jarrett's Avatar
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    Mark, welcome to the board. Nice ski. What kind of air intake are you using? I am interested in trying out a 4 inch intake as well. Thanks.

  5. #5
    Just had a chance to test my ski again tonite. Installed a bow spray deflector, which works great, and a megaware keelguard. No difference in handling with the keelguard. Installed the 5 foot one. Also sent the impeller back to Impros to get repitched from 14/20 to 14/18.5. Acelleration is improved and ran 74.8 mph with 10 gallons of gas, water temp was 78 and air temp 80 degrees, smooth water @ 7450 rpm. Fluttered a couple times to 7500. 7 hours on the motor. Still have the OPAS on and no wedge. May need to pitch slightly steeper or install a smaller venturi nozzle. Will see how it runs in 90 degree weather and 70 degree weather. Was hoping for a few more mph with the stage 3. When I receive the permormance OPAS blockoffs and high flow hood I'll post results.

  6. #6
    I had also installed a boost gauge and ran 8 pounds of boost @ wot.

  7. #7
    hi mark

    did you mean 8450 fluttering to 8500? if so you need a little more pitch because you are hitting the rev limiter. ideally you will run 8400 for the best speed. by the time the tach reads 8450 you are at the rev limiter..

    mark
    race tech

  8. #8
    Gotta love this sport! 05Limited's Avatar
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    Hi Mark,

    Sounds like your ski is running with the best of them... congratulations!

    One thing caught my attention though. You said it ran 73.5 mph @ 8100 rpm with the 14/20 impeller and thought it might be slightly over-pitched. When you re-pitched it to a 14/18.5 you said it gained acceleration (as expected) and jumped to 74.8 mph @ only 7450 rpm.

    The reason I ask is I had Impros re-worked my stock impeller, but I had them "increase" pitch to bring "down" rpm. These pumps sure respond differently to tweeking than props on a performance boat outdrive.

    Keep us posted on your results... sounds like 76 is in your future.

    Jeff

  9. #9
    Gotta love this sport! 05Limited's Avatar
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    Darn Mark... that's too wierd!

    We weren't siamese twins seperated at birth, were we...

    Jeff

  10. #10
    Gotta love this sport! 05Limited's Avatar
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    Hey Mark (race tech),

    While your here, I have the RR IC, Riva air intake, 2.5 degree wedge, 158 degree thermostat, Impros prepped 12/19 impeller, and can hit 70 most anytime (with an all time high of 70.7). I am adding the Vortech SC impeller next week.

    My question is this. What can I expect by adding the race ECU? Does it actuallymake peak horsepower @ 8400 rpm as oppose to the stock peak at 8050?

    Thanks for any help... I think the ECU is next on my list.

    Jeff

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