Johnson 9.9 "Professionally" changed to 15hp

[NYGiants]

I am looking at a motor and the guy claims its a 9.9 professionally changed to a 15hp. is there anything other then the carb basically he changed if he did anything at all? its a 88 or 89
any way of me telling the difference in hp? and that hes not just full of it?

 

[billy4hp]

Re: Johnson 9.9 "Professionally" changed to 15hp

Although I don't know exactly what the change over entails. See if he still has the original 9.9 parts....

Some of the best info on the 9.9's/15's is found at this website http://www.sschapterpsa.com/ramblings/Ramblings.html , scroll down to item 90 or so...

Good luck...

 

[BigB9000]

Re: Johnson 9.9 "Professionally" changed to 15hp

Could have just swapped powerheads?

I have a 5hp seaking, which I professionally changed to an evinrude 6hp.

by changing I mean I bolted the 5hp power head onto my 1968 6hp evinrude shell. bam! 6hp ;-)

 

[soundchaser]

Re: Johnson 9.9 "Professionally" changed to 15hp

from what I understand it's not as easy as everybody thinks. I think you have to make exhaust changes, carb change and possibly intake change. But that's just hear say.

 

[1946Zephyr]

Re: Johnson 9.9 "Professionally" changed to 15hp

Could have just swapped powerheads?

I have a 5hp seaking, which I professionally changed to an evinrude 6hp.

by changing I mean I bolted the 5hp power head onto my 1968 6hp evinrude shell. bam! 6hp ;-)

Yep, on your's, that's all you would have to do. The 9.9 and 15hp's are the same cubes, so there would be some differences in carburetion and the intake manifold.

 

[bktheking]

Re: Johnson 9.9 "Professionally" changed to 15hp

Yep, on your's, that's all you would have to do. The 9.9 and 15hp's are the same cubes, so there would be some differences in carburetion and the intake manifold.

The 15's also had a tuned exhaust, they changed it from a square to a a round exhaust, the only way to tell is to drop the lower unit or pull the powerhead. Carb part # will allow you to cross reference to see if it's a 9.9 or 15 carb, the other way is to look inside the carb throat, they are larger than the 9.9.

 

[R.Johnson]

Re: Johnson 9.9 "Professionally" changed to 15hp

Why not ask the professional what he did? Would'nt any engine that has been in an authorized shop been profeffionally changed? I would walk away from anybody tried that line on me.

 

[tashasdaddy]

Re: Johnson 9.9 "Professionally" changed to 15hp

i have searched for data, confirming, changing carbs, makes a 15hp. i have found no data, where the motor has been put on a Dino and tested. what you are looking at is a bastardized motor, when it come to service, there is no telling what has been done to it.

 

[NYGiants]

Re: Johnson 9.9 "Professionally" changed to 15hp

would there be serial numbers on the powerhead or carb to tell that theyre different from a 9.9?

 

[bktheking]

Re: Johnson 9.9 "Professionally" changed to 15hp

would there be serial numbers on the powerhead or carb to tell that theyre different from a 9.9?

The powerheads were the same, there might be a tag on the carb or a casting number but usually a tag under one of the screws for the carb bowl. Still doesn't mean much, just bolting on a 15hp carb can make matter's worse, it all has to be in line to make it a 15.

 

[NYGiants]

Re: Johnson 9.9 "Professionally" changed to 15hp

I talked with the seller today, and he told me that that carb and "all that" was changed by a marina. Now i know it is controversial on whether or not it makes it 15hp, but in your opinion does it? he also said that it has been used changed

 

[tashasdaddy]

Re: Johnson 9.9 "Professionally" changed to 15hp

"all that" makes it a Bastardized 9.9. i would not touch it with out, an copy of the invoice from the marina who did it. as a mech, i have no idea, what has been done, when you bring it to me to fix it.

 

[kenmyfam]

Re: Johnson 9.9 "Professionally" changed to 15hp

Personally I would walk away.
Just my 2 cents though.

 

[kbait]

Re: Johnson 9.9 "Professionally" changed to 15hp

If your water isn't frozen, take it for a spin. If you like the performance, and the price is right, go for it.

 

[NYGiants]

Re: Johnson 9.9 "Professionally" changed to 15hp

well the motor is on the back of a boat right now. and its 1200 for the combo. i am interested mainly in the boat, and i definitely will want to see the engine run. and i suppose i can always sell the motor and buy a 15hp for not too much of a price difference

 

[ChrisAG]

Re: Johnson 9.9 "Professionally" changed to 15hp

just bolting on a 15hp carb can make matter's worse, it all has to be in line to make it a 15.

They only went with tuned exhaust for the 15 for 1981 and newer. Prior to that the exhaust was the same.
1979-92 the 15 had intake reed shims, the 9.9 did not.
1974-78 only difference was the carburetor, so swaping it out will give you what was then sold as a claimed 15hp.

OMC changed carb designs at least once in that generation of engine, so if you swap carbs they must be of the same vintage, as later will not fit on older and vice versa. Not sure when the carbs were redesigned.

That said, who knows what parts are on that engine... at the very least you'd need to test it on the water.

 

[bktheking]

Re: Johnson 9.9 "Professionally" changed to 15hp

They only went with tuned exhaust for the 15 for 1981 and newer. Prior to that the exhaust was the same.
1979-92 the 15 had intake reed shims, the 9.9 did not.
1974-78 only difference was the carburetor, so swaping it out will give you what was then sold as a claimed 15hp.

OMC changed carb designs at least once in that generation of engine, so if you swap carbs they must be of the same vintage, as later will not fit on older and vice versa. Not sure when the carbs were redesigned.

That said, who knows what parts are on that engine... at the very least you'd need to test it on the water.

My point exactly, just throwing a 15hp carb on a late model 9.9 doesn't make it a 15, in fact it makes it difficult to use at trolling speed as they tend to deliver too much gas. At this point it's part of the price of the boat, if it proves to be a POS part it out on ebay and get another motor.

 

[tashasdaddy]

Re: Johnson 9.9 "Professionally" changed to 15hp

"They only went with tuned exhaust for the 15 for 1981 and newer." exactly, and this is an 88 or 89. we have no idea what the changed."

as i have said before, there is not any document evidence this works.

 

[NYGiants]

Re: Johnson 9.9 "Professionally" changed to 15hp

thanks for all the help
looks like i'll sell the motor on CL.
how much should i ask?

 

[ChrisAG]

Re: Johnson 9.9 "Professionally" changed to 15hp

its a 88 or 89

Somehow missed that...