# Tell me why I can't use a 4strk prop on a 2strk



## Brett (Jul 16, 2008)

Pitch is pitch, and diameter is diameter. It's not the blades.
I wonder if the exhaust openings are different.
Could be different lower units on the 2 types.


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## B.Lee (Apr 29, 2008)

Tell us what motors we are comparing, and I'll tell you why.  

Most times it's as simple as needing the correct thrust washer for the prop application, sometimes they are completely different.


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## TomFL (Oct 2, 2007)

> Tell us what motors we are comparing, and I'll tell you why.
> 
> Most times it's as simple as needing the correct thrust washer for the prop application, sometimes they are completely different.


4-stroke merc 25 efi 2006
2-stroke merc 25 1994 and 1998

can PM serial #'s if you like

-T


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## Un-shore (Sep 27, 2007)

When 2 strokes are phased out there will be tons of 2 stroke props out there and they won't be able to sell any 4 stroke props.

I dunno, are the pitches the same or do the 2 stroke turn at higher RPM so the pitch would be different from 4 stroke?


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## Brett (Jul 16, 2008)

I wonder if you could press the spline out of the hub from one prop
and press it back into another. That'd be something any machine shop could do.
Yes, no, maybe?


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## costefishnt (Dec 11, 2006)

i know my 07 merc efi 4 stroke woud not accept any props from merc 2 strokes. the spline was completly different.

brett, you can swap hubs for just about any prop (within reason)


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## Brett (Jul 16, 2008)

Cool, I see me and my micrometer wandering around prop shops
looking for similar size hubs and exhausts. That ought to confuse
the sales guys. I'm so easily entertained.


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## TomFL (Oct 2, 2007)

> i know my 07 merc efi 4 stroke woud not accept any props from merc 2 strokes. the spline was completly different.
> 
> brett, you can swap hubs for just about any prop (within reason)


That's what I had always heard as well, but the props are interchangeable between the three motors. Would be worth checking final drive ratios to see how the pitch would work between motors before going further with hub swapping. 

-T


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