Yamaha outboard propeller questions

Jack Hammer

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Hey guys. I’ve got a couple questions regarding propellers. Hoping somebody will share some wisdom. I’m trying to prop my 40 hp two-stroke Yamaha on my Livingston 14. It’s a 13 spline shaft. A buddy of mine was kind enough to share some propellers with me to test. A couple of them are Yamaha and a couple are Honda. They all fit on the shaft as far as the spline is concerned. Does anyone know if I can use a Honda prop on a Yamaha if I use spacers and it fits on the shaft properly?

Also, as far as propeller diameter. Is there a minimum amount of space that is required between the end of the blade and the cavitation plate? Does it need an inch, half an inch clearance? Or is it fine even as close as a quarter of an inch as long as it’s not hitting capitation plate?

Thanks,
Lowell
 
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onehottip

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Jack I’m not a expert but, what I know is if it fits that half of the equation. The second and maybe most important is being able to get the motor up to wide open throttle ( wot )and being within the mfg spec of wot. Example wot 5200 thru 5800. Your motor mfg has a a wot spec if that prop will put you within those number your good. I hope that makes sense . The reason is that the prop size will make your motor most efficient and to not make the motor lug or over rev. Proper size is the gearing for your specific boat and motor pkg. so again if it fits along with wot spec your golden.
 
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Jack Hammer

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Thanks Bill that definitely makes sense. I am aware of the WOT target range. I just wasn’t sure if I could mix props for different engine manufacturers. Thanks for your reply.

Lowell


Jack I’m not a expert but, what I know is if it fits that half of the equation. The second and maybe most important is being able to get the motor up to wide open throttle ( wot )and being within the mfg spec of wot. Example wot 5200 thru 5800. Your motor mfg has a a wot spec if that prop will put you within those number your good. I hope that makes sense
 
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Reel Kahuna

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As long as it clears, then you're good to go. As for using a Honda prop on your Yamaha, if the splines matches and the prop fits snug with no slop, then using spacers to tighten on the prop shaft is again, good. As mentioned WOT is the determining factor as to what pitch is needed.
 
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onehottip

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Bottom line how much would a new yami prop cost? 80$.....
If the Honda isn’t where u need to be. If your close run it.
 
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Jack Hammer

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I get it. The only reason I inquired was a friend loaned me 4 different props of various different sizes and pitches. Honda and Yamaha. I was just wondering if I could test with the Honda props with causing any damage. Being able to test the various configurations just gives me more data.


Bottom line how much would a new yami prop cost? 80$.....
If the Honda isn’t where u need to be. If your close run it.
 
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onehottip

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That’s perfect being able to test all those different prop. Give um all a good test. The one nearest top of wot is the one I would choose. Good luck
 
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Reel Kahuna

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... Give um all a good test. The one nearest top of wot is the one I would choose. Good luck

Remember that each inch of pitch is worth about 200 rpm. Lowering the pitch will increase rpm and vice versa. For example, going from a 23 pitch to a 21 pitch will increase engine rpm by about 400 revolutions.
 
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