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  1. #1
    inteljd's Avatar
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    Leaning out at WOT -- Injector size?

    My 2005 RXP is running awesome but I'm leaning out at WOT. I just installed a Wabro fuel pump, Rotax Racing ECU, Valve Upgrade, 50lb Injectors, and running a RRFPR set at 80lbs base pressure. Everything is great until about 3/4 throttle, my AFR is showing 11.8 - 12.4 up to 3/4. From 3/4 to WOT I'm running at 14.3 to 15.4, I only stay on it long enough to stabalize. Do I need bigger injectors? Keep in mind that my evelation is 3000ft above sea level... I really don't want to push more than 80lbs on my RRFPR do I?


  2. #2
    Richieb's Avatar
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    Too much base pressure. You will damage the sealing of the pintle valve on the tip of the injector.

    Doesn't it say you should have 60lb injectors with a Rotax Racing somewhere on the 4-tec parts site.

    I am sure the 50lb ones will no where near be enough. Try 55's at least.

    Better too rich than holes in the pistons.

    Injectors to 60lb imo, and base to 58-60psi.

  3. #3
    speedskixp's Avatar
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    Quote Originally Posted by inteljd View Post
    My 2005 RXP is running awesome but I'm leaning out at WOT. I just installed a Wabro fuel pump, Rotax Racing ECU, Valve Upgrade, 50lb Injectors, and running a RRFPR set at 80lbs base pressure. Everything is great until about 3/4 throttle, my AFR is showing 11.8 - 12.4 up to 3/4. From 3/4 to WOT I'm running at 14.3 to 15.4, I only stay on it long enough to stabalize. Do I need bigger injectors? Keep in mind that my evelation is 3000ft above sea level... I really don't want to push more than 80lbs on my RRFPR do I?
    You definitely dont want your base pressure that high. I assume you started with your pressure lower and then started raising it and wound up at 80 and its still lean? Or did you start high? What rpms are you seeing? It kinds sounds like your on the limiter.
    Are these the injectors I sold you? If so, they are 48s.

  4. #4
    TEX-X's Avatar
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    i thought that the computer will decrease fuel when it's on the limiter

  5. #5
    Having Fun jp1300r's Avatar
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    What Rotax Racing ECU do you have? I thought they run 42's or 60's depending on the ecu not 50's.

  6. #6
    Having Fun jp1300r's Avatar
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    Don't run WOT at > 14:1 to see if it stabilizes. You are going to damage the engine somehow very soon.

  7. #7
    speedskixp's Avatar
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    Quote Originally Posted by TEX-X View Post
    i thought that the computer will decrease fuel when it's on the limiter
    It does
    Quote Originally Posted by jp1300r View Post
    What Rotax Racing ECU do you have? I thought they run 42's or 60's depending on the ecu not 50's.
    The 04-05 RR ecu's are mapped for 42s but being that he is running a big charger he is running bigger injectors..

  8. #8
    Having Fun jp1300r's Avatar
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    You would think he would be okay with the 50's, but hes not. Especially at his elevation. Weird.

  9. #9
    speedskixp's Avatar
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    Quote Originally Posted by jp1300r View Post
    You would think he would be okay with the 50's, but hes not. Especially at his elevation. Weird.
    Yeah, thats why I'm wondering if he is on the limiter. BTW. I think he's running 48s....
    Although during the good weather months here the 48s were not enough on JKs rotax ecu boat with the 68-140. We are running 50s in his boat now and the a/f is fine with a wot pressure around 75lbs. It is possible that those injectors just are'nt enough but if he has to go any bigger the idle and mid are gonna start to suffer.

  10. #10
    inteljd's Avatar
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    After talking to Rotax today they said that it is a must to run 60lb injectors, I'm running the Rotax Racing 4501 ECU with 50lb injectors. I will not be running my ski until I get those 60lb injectors, drop the RRFPR down to 60lbs instead of 80 and see how the numbers come out then. I should be able to test this on Friday.

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