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  MONTAUK: 90-HP Prop pitch

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Author Topic:   MONTAUK: 90-HP Prop pitch
Mark D posted 03-13-2004 05:41 PM ET (US)   Profile for Mark D  
I currently use 13x15 stainless prop on my 17 Monatuk with a 90-HP Yamaha. It came with the motor. It it will rev well over the 5500 RPM max.

I got a 13 x 19 stainless. Never put it on. Is it too much pitch?

jimh posted 03-13-2004 08:44 PM ET (US)     Profile for jimh  Send Email to jimh     
Many 90-HP engines come with a 17-inch propeller. The only way to determine if the 19-inch propeller is too tall for your set up would be to try it.
Mark D posted 03-13-2004 10:37 PM ET (US)     Profile for Mark D    
I did search seems this question was asked before:

http://continuouswave.com/ubb/Forum4/HTML/000973.html

Thanks

AQUANUT posted 03-14-2004 12:18 AM ET (US)     Profile for AQUANUT  Send Email to AQUANUT     
fyi....the new montauk 170's...90 hp two strokes come with stock alluminum....21p prop
AQUANUT posted 03-14-2004 12:18 AM ET (US)     Profile for AQUANUT  Send Email to AQUANUT     
fyi....the new montauk 170's...90 hp two strokes come with stock alluminum....21p prop
JayR posted 03-14-2004 04:08 AM ET (US)     Profile for JayR  Send Email to JayR     
My buddy uses that prop and it is too much. He is switching to a 13 3/4 x 17 as soon as possible.
JayR posted 03-14-2004 04:09 AM ET (US)     Profile for JayR  Send Email to JayR     
Sorry, he is going to the 13 3/4 x 15 or the 13 1/4 x 17. Max rpm with the 19 is 5100 rpm's.
Clark Roberts posted 03-14-2004 08:34 AM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
Mark, you don't say how many rpm (well over 5500}. Usually an inch of pitch gives 200 rpm either up or down so you can figure roughly from that. So the 19" is 4" taller than the 15" and should reduce rpm at WOT by approx 800rpm. Most Montauks (classics) around here, with 90 Yamahas, run 15" props and only one that I can think of runs a 17" and can hit only 5400 rpm. Might be a good idea to check the accuracy of your tach! Happy Whalin'... Clark.. Spruce Creek Navy
PS>lots of good prop advice on this forum by lots of knowledgable folks and you will find a unanimous opinion that underproping (unable to attain recommended top RPM figures) will eventually kill the engine (from detonation, over temp, carbon build-up etc). Even if not run wide open the engine will be lugging from the moment you put it in gear.
Clark Roberts posted 03-14-2004 08:39 AM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
Ooops, should have written "overproping" (unable to attain top recommended rpm).. not underproping

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