Evinrude 9.9 to 15hp conversion

[Louis123]

I have not been able to find much info on converting a 9.9 to a 15hp engine. It appears that all this is required is a new carb (slightly larger throat than the 9.9 carb. <br /><br />Does anyone have any real experience with this modification. I recieved info from one online marine store that said it would not increase power much and the engine would run rough. <br /><br />If that is true why did Evinrude offer the 15hp engine? I can't believe the factory 15hp was that bad.<br /><br />Appreciate any input on the subject. If I move ahead with the conversion I could really use a source for the carb.<br /><br />Thanks everyone.

 

[Paul Moir]

Re: Evinrude 9.9 to 15hp conversion

It depends heavily on the year, but I think in '78 it was just a carb swap. Go look at:<br /> http://www.evinrude.com/en-US/Accessories/Engine.Diagrams.htm <br />And check to see. Pay attention to intake manifold parts, block p/ns, exhaust covers, and exhaust tuners (inside the mid-section), and ignition parts.<br /><br />Later engines were set up with different exhausts and intakes and such, so just swaping the carb on them made them rough, etc.<br />Search this forum for "15 9.9". There's lots of reading there.

 

[Louis123]

Re: Evinrude 9.9 to 15hp conversion

Originally posted by Paul Moir:<br /> It depends heavily on the year, but I think in '78 it was just a carb swap. Go look at:<br /> http://www.evinrude.com/en-US/Accessories/Engine.Diagrams.htm <br />And check to see. Pay attention to intake manifold parts, block p/ns, exhaust covers, and exhaust tuners (inside the mid-section), and ignition parts.<br /><br />Later engines were set up with different exhausts and intakes and such, so just swaping the carb on them made them rough, etc.<br />Search this forum for "15 9.9". There's lots of reading there.

 

[Louis123]

Re: Evinrude 9.9 to 15hp conversion

Paul,<br /><br />Thanks for the link. I really found this info quite helpful. Need to do quite a bit more reading but think I can figure out what to do.<br /><br />Again Thanks.

 

[pjohn323]

Re: Evinrude 9.9 to 15hp conversion

Try this site for troubleshooting either the 9.9 or 15<br /><br /> http://www.wisnersinc.com/Fishing Info/Johnson_9.9_troubleshooting.htm

 

[umblecumbuz]

Re: Evinrude 9.9 to 15hp conversion

There's something else Louis, that hasn't been mentioned yet.<br /><br />The extra power given by the 15 is all at the top end, and the carb/exhaust/reed (on some motors) changes are all designed to produce increased revs.<br /><br />Both the 9.9's and the 15's are bulletproof. It all depends on what you want. Once you've priced out the parts, you might find you're better off selling your 9.9 and buying a 15.