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Subject: TWL: Re: Re: "Upgrading" outboards
From: Alex Hirsekorn (alexh@XXX.XXX)
Date: Fri Aug 02 2002 - 21:03:07 EDT
----- Original Message -----
From: "Steven Dubnoff" <sdubnoff@XXX.XXX>
>
> The consensus seems to be that, although these are built on the same
block,
> many parts (cams, carb jets, lower unit and so on) may differ between the
> models.
>
Hi Steve,
Your newsgroup search seemed like such a good idea that I decided to do a
similar web search. I used "9.9 to 15" on Google and came up with the
following Johnson/Evinrude references:
http://www.brokeboats.com/stuff.html
9.9 to 15 HP
If you are trying to increase your HP to 15hp simply switching a carb won't
do it without also switching the cylinder head as well. It would be way too
expensive to buy both items new(around 300 bucks or so). You should check
around at dealers, shops, and friends, etc. and try to locate a junk, blown
15 HP Johnson or Evinrude; both are same except for the paint. Remove the
carb and cylinder head and clean and rebuild the carb with a new kit; get a
new head gasket, and install em on your motor. You'll see quite a difference
in power.
http://www.myasylum.com/sbf/messages/186.html
Anyone have info for this, aside from the carburetor change? This is for a
1990 model. It was 11 years ago, but when I tried to do the "common"
conversion via carb swap only, it didn't work. Results were: raw fuel out
the exhaust, no significant power increase. After contemplating this for
several years, I have come to the conclusions: The exhaust tube for the 15hp
is different than the 10hp, the exhaust ports in the 15(exhaust housing
casting) may be different than the 10, the timing advance cam may be
different. There is absolutely no info regarding this in the service manual
or parts list except: I saw a different exhaust tube in a photo of something
unrelated in the service manual. Johnson went to the trouble of being sure
the necessary info was not available in their documents.
I also came across a couple of vague indications that nobody seems to know
_specifically_ how to do the mod to either Mercury or Yamaha engines.
All things considered, it would seem that the conversion isn't worthwhile
under ordinary circumstances. The idea of switching ID stickers for tax
purposes will be left to the individual's sense of ethics and gamesmanship.
Legendarily yours,
Alex
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