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  1. #1
    !!!! wave jumper !!!! 05_RXP's Avatar
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    rxp with x and external i/c rpm questions

    Hey guys I got some questions about my rxp rpms. Its a 2005 on the digital gauge it only reads in imcrements of 50 so 8000 8050 and 8100. Should it read in 10 or 20 rpm increments? Also my next question is I just put the external i/c and the rising rate on it was running rich up top at 11.2 to 11.3 at 8150 with a speed of 74mph. I ended up lowering pressure to 55.5 psi to get my afrs to 11.8-12. I went from 74 to 75.5 but my rpms never changed. How is this possible


  2. #2
    pass1's Avatar
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    Were you going in the same direction... with or against the current both times.

  3. #3
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    04-05's only go in increments of 50, 8100 is the number you are wanting...8150 bounces the limiter and cuts ignition...You got the AFR right which allowed you to probably sustain WOT for a longer time, hence your slight gain in speed...

  4. #4
    JFizzleJR's Avatar
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    You're running hard on the limiter Drew! Better watch your exhaust manifold bell if you keep riding without bringing the rpms down.

  5. #5
    Moderator Snoman's Avatar
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    Quote Originally Posted by 05_RXP View Post
    Hey guys I got some questions about my rxp rpms. Its a 2005 on the digital gauge it only reads in imcrements of 50 so 8000 8050 and 8100. Should it read in 10 or 20 rpm increments? Also my next question is I just put the external i/c and the rising rate on it was running rich up top at 11.2 to 11.3 at 8150 with a speed of 74mph. I ended up lowering pressure to 55.5 psi to get my afrs to 11.8-12. I went from 74 to 75.5 but my rpms never changed. How is this possible
    Your AFRs are spot on...11.8-12 is perfect..You picked up more speed because you generated more power by leaning out your AFRs and getting them right were they need to be..11.2-11.3 is rich for WOT apps..You probley gained RPMs but didnt see it because the 04-05 tach reads in 50 RPM increments...Tweek your prop down to 8100 and youll see some more speed out of your boat.

    I wouldnt worry about the bell on your exhaust manifold,90% of us have no bell left on ours....

  6. #6
    !!!! wave jumper !!!! 05_RXP's Avatar
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    i ran both ways up and down but i gpsed sitting still and my max speed was .1 mph.lol fastest the ski has ever gone. when it was running 11.2 it hit 74 both ways and then when i leaned it out to 11.8 it hit 75.5 both ways. but stayed at the same rpm. so you guys all think that 8100 is optimal rpm? everyone seemed to say 8150. instead of pitching the prop should i drop a ring size from 83 to 82mm or 81mm. i am not sure if i will have enough jam to spin 8100 with a 81mm nozzle

  7. #7
    JFizzleJR's Avatar
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    Quote Originally Posted by 05_RXP View Post
    i ran both ways up and down but i gpsed sitting still and my max speed was .1 mph.lol fastest the ski has ever gone. when it was running 11.2 it hit 74 both ways and then when i leaned it out to 11.8 it hit 75.5 both ways. but stayed at the same rpm. so you guys all think that 8100 is optimal rpm? everyone seemed to say 8150. instead of pitching the prop should i drop a ring size from 83 to 82mm or 81mm. i am not sure if i will have enough jam to spin 8100 with a 81mm nozzle
    Go with the 81. IMO you are 200+ rpms into the limiter.

  8. #8
    !!!! wave jumper !!!! 05_RXP's Avatar
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    Quote Originally Posted by JFizzleJR View Post
    Go with the 81. IMO you are 200+ rpms into the limiter.
    not to question you but are you sure? i know with just the x and 14/19 i had no problem pushing 8200 so how could i be that far into the limiter and only be at 8150.

  9. #9
    JFizzleJR's Avatar
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    Quote Originally Posted by 05_RXP View Post
    not to question you but are you sure? i know with just the x and 14/19 i had no problem pushing 8200 so how could i be that far into the limiter and only be at 8150.
    You were at 8150 when the fuel was rich and you're at 8150 with the fuel corrected. You're 3+ mph slow. Your 14/19 had you on the limiter too.

  10. #10
    Water4fire's Avatar
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    Quote Originally Posted by JFizzleJR View Post
    You were at 8150 when the fuel was rich and you're at 8150 with the fuel corrected. You're 3+ mph slow. Your 14/19 had you on the limiter too.
    Yep.

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