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Thread: Yamaha RPMs ?

  1. #1
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    Default Yamaha RPMs ?


    For those of you who run Yamaha 50's, what RPMs are you turning at WOT? When I bought mine it had the wrong prop on it so I jacked the throttle up so it would plane out and I could fish the weekend. The end of the next week I got the right size prop in and I still havent got it zero'd back in. Im thinking it needs to be 5500-5800 sound right? At the moment I can run WOT w/ no trim and its hitting 6k and you can hear the rev limiter kicking in. If Iback down to 1/2-3/4 throttle and trim it 1/4-1/2 up the its all fine(RPMs in these cond. are anywhere from 55-5800). The boat is a 16ft G3.
    Its Foolish and wrong to morn the men who died, instead we should thank God that such men lived.
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  2. #2
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    Quote Originally Posted by duckkiller View Post
    For those of you who run Yamaha 50's, what RPMs are you turning at WOT? When I bought mine it had the wrong prop on it so I jacked the throttle up so it would plane out and I could fish the weekend. The end of the next week I got the right size prop in and I still havent got it zero'd back in. Im thinking it needs to be 5500-5800 sound right? At the moment I can run WOT w/ no trim and its hitting 6k and you can hear the rev limiter kicking in. If Iback down to 1/2-3/4 throttle and trim it 1/4-1/2 up the its all fine(RPMs in these cond. are anywhere from 55-5800). The boat is a 16ft G3.
    17' flat bottom Duracraft, stick steer....Trimmed up half way on Yamaha trim guage...13 pitch prop......5600 rpm. 50hp 2 stroke Yamaha..
    USS Intrepid CVS-11 Helicopter Squadron-3 1960-1964

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  3. #3
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    Sounds as though your prop is too small for the weight it's pushing. Are you tiller steer, console with a wheel, or stick steer? You're probably a borderline 15 pitch prop for that size boat with that engine. Try running it width a very heavy friend on board and see what happens.

  4. #4
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    Im a console steer. Ive run it by myself and w/ a load and no matter what it does the same. The prop that was origonally on the boat was a 10x15-G and the new prop they sent me is 10 5/8 x 12-G and both props are alum
    Last edited by duckkiller; 04-19-2009 at 10:31 AM.
    Its Foolish and wrong to morn the men who died, instead we should thank God that such men lived.
    General George S. Patton Jr

  5. #5
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    my Mercury 50hp runs topped out around 5500 .....it is on plane at around 4000 though..I do not have to run at full throttle to be on "top" of the water

    my 2 cents...

  6. #6
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    What was your tach reading with the 15 pitch prop?

  7. #7
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    15pitch wouldnt plane it out, so I called the dealer I bought from(used boat) and he sent me the 12 pitch free of charge. I adjusted the throttle to get the 15 on plane but I dont remember the RPMs. Best of my memory I think it was still high
    Its Foolish and wrong to morn the men who died, instead we should thank God that such men lived.
    General George S. Patton Jr

  8. #8
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    If you know of someone who will loan you a stainless 13" pitch to try, I think you will see a noticeable difference. The 12" is too small , otherwise your rev limiter would not come into play.

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