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  1. #1

    inconsistant rpm in the heat

    OK, I have had my 05 rxt for 2 weeks and it has been working great running 8100rpm and 70 mph at anytime until yesterday. It now runs to 7900 rpm and 68mph but will creep slowly to 8000. It has warmed up from 75deg to 90 deg. will this have this much effect on the performance or are the dreaded washers on their way out?
    I checked the impeller and it looks fine and doesn't cavetate out of the hole. It seems like it has lost a little hp but I know on my sled the heat will effect it just not sure on the 4 stroker.


  2. #2
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    Quote Originally Posted by Kragar View Post
    OK, I have had my 05 rxt for 2 weeks and it has been working great running 8100rpm and 70 mph at anytime until yesterday. It now runs to 7900 rpm and 68mph but will creep slowly to 8000. It has warmed up from 75deg to 90 deg. will this have this much effect on the performance or are the dreaded washers on their way out?
    I checked the impeller and it looks fine and doesn't cavetate out of the hole. It seems like it has lost a little hp but I know on my sled the heat will effect it just not sure on the 4 stroker.

    Congrats! You have just experienced HEAT FADE!

    Get those washers swapped out to metal anyway...

  3. #3
    Quote Originally Posted by Kragar View Post
    OK, I have had my 05 rxt for 2 weeks and it has been working great running 8100rpm and 70 mph at anytime until yesterday. It now runs to 7900 rpm and 68mph but will creep slowly to 8000. It has warmed up from 75deg to 90 deg. will this have this much effect on the performance or are the dreaded washers on their way out?
    I checked the impeller and it looks fine and doesn't cavetate out of the hole. It seems like it has lost a little hp but I know on my sled the heat will effect it just not sure on the 4 stroker.
    Yes, many weather factors will affect you. RAD (Relative Air Density) is HUGE in affecting RPM and speed. Hot and humid days will lower your RPM and speed. Warm water will reduce your intercooler's efficiency. Are you running any mods? If not, you're not seeing 70mph for starters, but anyways the more you mod the more your machine will react to changes in RAD.

  4. #4
    those are speedo numbers abbd I realize they are not correct by they are consistant from day to day. The ski is completly stock. It will comeaprt this winter for the washer upgrade. It only has 35hours on it right now.

  5. #5
    eclipsecleaning's Avatar
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    my washers blew at 35 hours and f-d up my ski bad

  6. #6
    Site Admin Green Hulk's Avatar
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    Going with a 158 degree thermostat helps with heat fade tremendously

    Riva kit
    http://www.4-tecperformance.com/inde...roducts_id=305

    Or complete Rotax Racing thermostat
    http://www.4-tecperformance.com/inde...roducts_id=295

  7. #7
    sourpower RXT's Avatar
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    whats difference between these 2 thermostats??

  8. #8
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    Quote Originally Posted by sourpower RXT View Post
    whats difference between these 2 thermostats??

    The RIVA one replaces just the thermostat itself, and you need to modify the housing to do so...

    The Rotax unit is all together, just unbolt the old one, bol tin the new one...no modification needed.

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