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  1. #1

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    Need input on evolving my Rude1 built 04RXP

    Hello all. I'm new to the forum and just getting started with 4tec skis. I recently purchased a 2004 RXP with a good baseline of mods from a forum member. I've already got the bug to go further so I need some input. Current mods are:

    Rude1 charger: Seeing 11psi at 8100
    4" Kanaflex intake w/R&D adapter
    Rotax Racing Intercooler
    Greenhulk ? waterbox
    Rotax Racing 42lb injectors
    RRFPR
    Walbro fuel pump
    Stock ECU
    Pump Wedge
    Speedfreeks Impeller
    Ride Plate holes filled
    Riva Grate
    Speedfreeks bellow band
    ProComp Boost gauge
    OPAS delete

    Ordered and on the way: CMD/WB2 setup with AFR gauge and bung in the Jpipe

    Currently I'm getting 76-77mph consistently on my GPS. My goal is to go 80+ reliably on a recreational ridden ski.

    Motor has never been opened. Currently has 190 hours on it with stock valves. First up in the off season is an upgraded valve train.

    Wish list: Here's where I need input......keep in mind I'm looking to complement what I have and not redo everything.

    Supertech Valves, springs, retainers ?
    Go with head studs or just head bolts ?
    Head porting: Who is good? Anyone have experience with Speedfreeks on porting?
    Cam - May grab the Rotax 4224 for sale in marketplace if it makes sense. Thoughts?
    Riva ECU - 8650 ? 50 lb ? or Rotax Racing ECU ? I'm worried about the lack of Knock sensor function on the RR.
    What are the right sized injectors with these additions?
    Do I need to worry about the bottom end at 190 hours?

    Right now I run 8100 rpm. I'm thinking that if I get it to 8500-8600 that would be about right?

    Thanks for your support everyone !


  2. #2
    dpracing's Avatar
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    The valves are ticking time bombs, good thing you're going to change them ASAP

  3. #3
    Moderator Snoman's Avatar
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    Quote Originally Posted by TheBernards View Post
    Hello all. I'm new to the forum and just getting started with 4tec skis. I recently purchased a 2004 RXP with a good baseline of mods from a forum member. I've already got the bug to go further so I need some input. Current mods are:

    Rude1 charger: Seeing 11psi at 8100
    4" Kanaflex intake w/R&D adapter
    Rotax Racing Intercooler
    Greenhulk ? waterbox
    Rotax Racing 42lb injectors
    RRFPR
    Walbro fuel pump
    Stock ECU
    Pump Wedge
    Speedfreeks Impeller
    Ride Plate holes filled
    Riva Grate
    Speedfreeks bellow band
    ProComp Boost gauge
    OPAS delete

    Ordered and on the way: CMD/WB2 setup with AFR gauge and bung in the Jpipe

    Currently I'm getting 76-77mph consistently on my GPS. My goal is to go 80+ reliably on a recreational ridden ski.

    Motor has never been opened. Currently has 190 hours on it with stock valves. First up in the off season is an upgraded valve train.

    Wish list: Here's where I need input......keep in mind I'm looking to complement what I have and not redo everything.

    Supertech Valves, springs, retainers ?Supertechs are good..probably the best out there right now
    Go with head studs or just head bolts ?This is pure preference as some are runniing new bolts with no issues..i recommend head studs though
    Head porting: Who is good? Anyone have experience with Speedfreeks on porting?
    Cam - May grab the Rotax 4224 for sale in marketplace if it makes sense. Thoughts?you can go with a cam,BUT many have reached 80 mph with the stock cams including myself,save your money on the cam and go with a bigger Scer
    Riva ECU - 8650 ? 50 lb ? or Rotax Racing ECU ? I'm worried about the lack of Knock sensor function on the RR.If your worried about the knock sensor then go with Riva if you can find one....otherwise a reflash will keep the knock sensor also..
    What are the right sized injectors with these additions?Seeing you will probably need a bigger Scer to acheive these speeds you will want to go with the injectors that compliment the boost/AFRs..
    Do I need to worry about the bottom end at 190 hours?
    At 190 hours it would not hurt to freshin up the bearings and rings seeing your gonna want to spin higher RPMs...also you should have the flywheel bolts replaced too as they have had issues in the older skis breaking..

    Right now I run 8100 rpm. I'm thinking that if I get it to 8500-8600 that would be about right?

    Thanks for your support everyone !
    You will also need a new prop or one repitched for the higher RPMs also...dont forget to get an Air Fuel Ratio guage as running this kind of setup it is almost essential to have this for tuning..without it you could lean out before you know it and lose your motor..

  4. #4
    West Texas RXP skoepp's Avatar
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    +1 to snows comments.
    On the charger I would get a 2 rude upgrade without a doubt. $
    $ - cost less for a wheel and front sc cover.
    Then having buy an entire charger.
    Plus a R1 want be worth alot so use the housing and save some $

  5. #5

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    Quote Originally Posted by dpracing View Post
    The valves are ticking time bombs, good thing you're going to change them ASAP
    Absolutely. I've read a lot about the valves. I cross my fingers every time I go out. Kind of taking it easy right now. My CMD/WB2 is on the way so I'm planning to hook it up and install the AFR gauge to get some data on the current setup. Then I'll start the disassembly. Valves are top of the list.

  6. #6

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    Snowman and skoepp - thanks for the responses. Sounds like the Supertechs are the way to go. That'll be first.

    Any advice on porting of the head?

    Right now my prop was repitched by Speedfreeks. I was told it is 21.5 pitch. You think that will need to be redone?

    I'm thinking hard on the cam. I hear the idle sounds nasty ! I've always had good cams in my cars. Decisions decisions.

    For an ECU how close to the rev limiter should I set up for? For example if I plan to run 8500 do I buy a 8650 ECU or higher?

    And I'd like some opinions on the knock sensor function. Is it risky to run the rotax ECU without knock in a recreational ski?

  7. #7
    West Texas RXP skoepp's Avatar
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    Welcome to the forum!


    Slow 91 for the head work.
    I would run 100 rpm or more below rev limiter.
    You already have either a 28 or 29 cam.
    Don't forget to upgrade your R1 for the R2.
    Keep that prop and get it massaged once you see where your rpms shake out. More then likely you will have to depitch the prop a little to get to 8500 rpm.

  8. #8

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    Quote Originally Posted by skoepp View Post
    Welcome to the forum!


    Slow 91 for the head work.
    I would run 100 rpm or more below rev limiter.
    You already have either a 28 or 29 cam.
    Don't forget to upgrade your R1 for the R2.
    Keep that prop and get it massaged once you see where your rpms shake out. More then likely you will have to depitch the prop a little to get to 8500 rpm.

    Thanks ! The forum is great. Tons of info and knowledge here. I've been reading and seen Slow 91 a bit. Seems that many are happy with his work so Ill send him a message. Making good progress on my plan so far. I've seen a lot of guys happy with the 29 cams too so prob stick with that. I think the rude2 just got added to my list too . Wife's gonna be pissed. Oh well!

  9. #9
    West Texas RXP skoepp's Avatar
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    There was a R2 in the classifieds from a reliable seller WFO for 625 shipped.

  10. #10
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    If you freshen the motor, then also do the following for the 04 block...

    - Upgrade Flywheel bolts http://www.4-tecperformance.com/inde...roducts_id=693
    - Replace oil jet in block, especially if plan to run high RPM http://www.4-tecperformance.com/inde...roducts_id=387
    - Replace the Rotax Racing IC with something more efficient, such as the Fizzle HE or a custom unit. The Rotax's (although good) are corks, per my flow work in the past...http://www.greenhulk.net/forums/showthread.php?t=97790

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