Question about a Evinrude/Johnson 9.9 vs Johnson/Evinrude 15

Some manufactures made one engine and then detuned it by putting a restricted carb on it.This was to save money in retooling costs.

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BASSBOY1 [anouncer voice off]

We have talked about similar deals a couple times. I think it varies widely with the year and models so its hard to give you a defnitive answer on what you have to do.

Here is a thread from last year, maybe it has something useful in it for ya.

https://www.tinboats.net/forum/viewtopic.php?f=4&t=4111

Andy said:

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BASSBOY1 [anouncer voice off]

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Haven't seen him on here in a few days. :shock:

OMC built both Evinrude and Johnson motors. The 9.9 is just a derated version of the 15 to comply with lakes that have a 10HP limit restriction. The carburator is the difference between the 9.9 and the 15.

ben2go said:

Andy said:

[anouncer voice on] THIS LOOKS LIKE A JOB FOR........ DUM DUM DA DUM DUM.....

BASSBOY1 [anouncer voice off]

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Haven't seen him on here in a few days. :shock:

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We gonna have to get the dogs out?

Trust me it is not just a carb change out. There are a lot of different parts to make a 9.9 into a 15. I have a 85 Evinrude 15 hp and I love that little motor. I have been extensively looking at parts pages and other things because I found a 9.9 I was going to get as a backup and add hp but the cost to do it with new parts is almost the same as finding a 15 hp to buy. I think I have about 250.00 in my motor after buying boat motor and trailer together. Find a 15hp.

There were a few years that the carb swap was the case. Don't ask me which years they were, as I don't know. However, the fact that one person could do that fueled everybody that had a 9.9 OMC into thinking they could be the same, and the internet really pushed that. Think more in terms of carb, exhaust, among other things. The thing I like is how the 9.9 and 15 are the same size, so you can put a 9.9 cover on a 15 horse motor to sneak into hp limited lakes......

ben2go said:

Andy said:

[anouncer voice on] THIS LOOKS LIKE A JOB FOR........ DUM DUM DA DUM DUM.....

BASSBOY1 [anouncer voice off]

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Haven't seen him on here in a few days. :shock:

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Sorry. There was a last minute unexpected opening in my scout troops 4 day Okeefenokee swamp canoeing trip. I had been 2nd on the waiting list for more than a month, and 3 people got sick within a matter of hours of departure time, so I had very little warning.

timsmcm said:

Trust me it is not just a carb change out. There are a lot of different parts to make a 9.9 into a 15. I have a 85 Evinrude 15 hp and I love that little motor. I have been extensively looking at parts pages and other things because I found a 9.9 I was going to get as a backup and add hp but the cost to do it with new parts is almost the same as finding a 15 hp to buy. I think I have about 250.00 in my motor after buying boat motor and trailer together. Find a 15hp.

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Thanks! Could you name a few of those parts (if you don't mind)? Also, I wish [-o< I could find a 15 hp Rude or Johnson REASONABLY priced, but good luck. Have you visited Ebay lately & looked at what OB go for? Those folks are I-N-S-A-N-E! :shock:

bassboy1 said:

There were a few years that the carb swap was the case. Don't ask me which years they were, as I don't know. However, the fact that one person could do that fueled everybody that had a 9.9 OMC into thinking they could be the same, and the internet really pushed that. Think more in terms of carb, exhaust, among other things. The thing I like is how the 9.9 and 15 are the same size, so you can put a 9.9 cover on a 15 horse motor to sneak into hp limited lakes......

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Any idea BB where I might look to find the answer to the carb question (the years that they were interchangeable)? I mean like specific sites not just google. Is it an extensive & costly job to make the conversion & in your opinion, is it worth it (I.e. effort, time, money etc..)? Thanks

I found this right off. I'll keep searching whenever I get a chance.

https://www.outboardrepairs.com/topics/012551.html

BloodStone said:

Hello all

I went to a marine shop 45 miles from my house today to shop for another outboard motor for my 14' Sea King. And the guy told me that the 9.9 Evinrude (1973-1992) has the same power-head as the 15 hp. Is this true? Also, he said with some minor alterations (namely carburetor) that the 9.9 could equal the HP output of the 15 HP (he didn't know the exact specifics). Is this true? and how "minor" are we talking here?
Thanks

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That far back there were more than carb differences, I had a 1994 9.9 that was in fact a 15 with a restricted carb to reduce it to the 9.9 hp. This was all confirmed by OMC at the time, the dealer sold me the larger carb (much larger) bolted it on, adjusted the mix and I now had a 15 hp.
All timing, gear ratio, bore, stroke, and all else was the same. You may have to change the prop pitch as the 9.9 prop has less pitch, but it was only in those early to mid 90's that this conversion was just a carb.
Airshot