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  1. #1

    2003 Gtx-sc 6900 Rpm - Ok?

    Hi All - I would greatly appreciate some advice. Here is the story: I purchased an '03 GTX-SC in perfect cosmetic condition and only 28 hrs but it could only do 55 mph and I felt a bit of cavitation under acceleration (compression tested out as good and other little typical things checked out OK). I decided to take it on and work out the bugs, figuring that all models have nuances and I was going to install a level 1 upgrade kit anyway which would address the dinged impeller and wear ring issues.

    At the time of the test ride, it had 1.5 year old gas in it as it was kept in a garage for that time period without a ride. Here is what I did to it:

    1) Drained out all of the old gas
    2) Replaced the plastic pump with a new metal '04 version
    3) Installed a new wear ring with the new pump
    4) Installed a new 12/20 Solas impeller
    5) Installed a R&D 1.5 degree pump wedge
    6) Rotated the lower nozzle bushing per R&D instructions to get a little more pitch
    7) Installed the aluminum OPAS blockoffs and gutted the OPAS system
    Installed Riva finger throttle kit (first thing!)
    9) Installed new spark plugs (properly gapped)
    10) I only run 93 octane Chevron fuel
    11) The seller had the oil changed and new battery installed by a dealer before the sale; the oil is at the top of the fill range (I mention this because someone may say this is a contributor to my problem)
    12) Installed new front side oil pressure sensor and that stopped the "check engine" problem (code 1202 and glad it was not the rear)

    1) Great acceleration with no cavitation
    2) Handles much better with OPAS off
    3) Only get about 6900 to 7000 rpm at WOT (PROBLEM??? I don't recall the top rpm prior to installation of mods and the service manual indicates an expected range of 7250 to 7350)
    4) Only get about 58 to 59 mph on glass at WOT (PROBLEM???)

    I assume that 6900 rpm and only 59 mph is not the best that this machine should do. I have read several threads indicating that this machine should do around 7400 rpm and about 63 mph on glass, although one of the local SeaDoo guys said that what I am seeing is not abnormal.

    I raced an '06 RXP in 1 to 2 ft chop this weekend and he stayed on my back quarter but couldn't pass me. The acceleration of my machine is strong, it is just the top end that is a problem. I know that my advantage was the 3-seater hull in the chop as I expect an RXP to eat me alive on glass.

    Anyway, I can only think of 3 things that could be causing this problem:
    1) Slipping supercharger
    2) Too much oil (I'm going to drain a bit before my next ride)
    3) A little too much slack in the throttle cable at the body (there is about a quarter inch of play and I wil adjust that out before my next ride but I have manually depressed the cable at the throttle under WOT to take up any slack and it made no difference)

    Any thoughts or advice?

    Also, after dumping about $1,500 into it already, I am leaning on getting the supercharger upgraded to the '06 spec and adding the blowoff valve. I am in this deep already and want a reliable machine but I have also heard that the 2003 supercharger does not have the ceramic washer failure issue that subsequent machines do. On the other hand, I was told by someone that "early" '03s did not have the ceramics but later year '03 models did (depended on manufacture date).

    Anyway, considering the conditions I described above and considering that I don't mind spending another $500, should I feel compelled to have the supercharger rebuilt out of fear that I will blow the engine (or have the expensive oil pump issues) or do the SCs tend to give you a grace period between slipping and catostrophic damage?

  2. #2
    gtxscrider's Avatar
    Join Date
    May 2007
    If i were you i would go with the rebuild kit and throw in some metal washers and ceramic bearings for maximum reliability .

  3. #3
    gtxscrider's Avatar
    Join Date
    May 2007
    And since your in florida i recomend perry performance group they hooked me up with an entire sc rebuild all through my warrenty great people and great work.

  4. #4
    Dr Len's Avatar
    Join Date
    Jan 2006
    New Jersey Attitude Capital of the World
    The 03's Did not have ceramic washers.

  5. #5
    mjammer's Avatar
    Join Date
    Nov 2005
    Ft. Wayne, IN
    Check the SC with the torque test (described many places) and you also may want to check the impeller pitch in case it was off. An '03 SC runs 7600 +/- 50 RPM if all is right and should be low 60's. With what I have in my sig, my best has been 64.4.

  6. #6
    Kaybat's Avatar
    Join Date
    Aug 2005
    Ormond Beach,fl
    I wouldn't do so many mods at one time man, then you're left 2nd guessing what isn't right...if its a stock 03 SC, than their are no ceramic washers to fail....some of the tech's will chime in shortly....sounds like it might be oil level....Good Luck
    Last edited by Kaybat; 08-16-2007 at 03:16 PM.

  7. #7
    Banned User
    Join Date
    Dec 2006
    Crest Hill, IL
    - the SC, have PPG do the HD shaft upgrade with metal washers...03's don't have ceramics, but this upgrade will put you at 06' spec...

    - pull some oil, get it to about 1/2 stick...that there will get you 250-400 rpm right there...

    - Prop needs to be pitched, about 1mm out of it to start...This will get the rest of your RPM...

    Do those things, and you will be back to 7500-7600 rpm, where you should be...

  8. #8
    I drained some oil out tonight - down to about 1/4 up the fill range now. I will run it there on Saturday (crossing fingers).

    In the process of taking some slack out of the throttle cable, I broke the adjustment screw portion near the throttle body... corrosion was the culprit... keep that thing in a swath of grease... luckily PPG had one in stock. The local shops wanted me to pay freight from Canada for the cable... but only regular ground shipping from PPG. Living in the same state has its advantages. All my stuff from PPG is UPS ground and always arrives next day. I'll get it tomorrow so I should still make a Saturday run.

  9. #9
    Hi all - took a long break from the board... school, work, etc. Also winterized the ski since the last post.

    Anyway, even though I got the oil to the right level and installed the new throttle cable, still only about 6,950 to 7,000 rpm. The ski runs great... very strong accelerator -no hesitation... even though my buddy keeps up with me on his Ultra 150 (disappointing).

    1) I am sending the SC in for the stainless upgrade... will an upgraded SC wheel make much of a difference? Which to buy? There are several.

    2) I have heard that the 2003 GTX SC don't have ceramic washers and that some do... anyone confident that they know the real story?

    3) Does 60 mph at 6,950 rpm sound reasonable for this model considering the mods I have done?

    4) Do the cast pistons on this model limit it with regard to upgrading injectors, ECU, higher boost SC wheel, etc.? Don't want to trash it.

    I love this ski and it is mint... just love the layout of the GTX. Anyway - trying to decide whether to just sell as-is or dump another grand or two to make it rip... is that possible? Higher psi injectors, ECU, etc.? It is very hard to find a nice used RTX.

    Thanks much to anyone who can give me some advice here...

  10. #10
    It is very hard to find a nice used RXT.
    Maybe in Florida...

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