Any way to definitively tell between a johnson 9.9 and johnson 15 hp outboard?

[jimmwaller]

Hello,
I bought a used johnson outboard. The cowl cover says 9.9, and the manual it came with is from a 9.9, but the model number on the nameplate lists it as a 15. And, the nameplate looks way newer than the rest of the engine.

Just curious—is there any way to absolutely differentiate between a 9.9 and a 15 from the late 80s, early 90s? Some feature that one has that the other doesn't?

I could see it being the case that the cowl got replaced, or I could also see it being the case that the nameplate got replaced given that it looks newer and cleaner that the rest of the motor, both seem equally plausible to me. Any guidance would be appreciated. Thanks!

 

[racerone]

Post the model # and post some pictures.-----One quick way to tell is by size of high speed jet and carburetor bore.----Other than that they look identical on the outside.

 

[hardwater fisherman]

I believe the 9.9 carb will have a smaller throat then the 15. Someone may have changed out the hood to be able to go on hp restricted lakes.

 

[jimmwaller]

Thanks. I may have to dig deeper to get to the carb and measure the throat or needle, but maybe these photos will help:

IMG-3913

Image IMG-3913 hosted in ImgBB

ibb.co

IMG-3914

Image IMG-3914 hosted in ImgBB

ibb.co

plate says that the model number is: J15RESR

Thanks

 

[racerone]

Yes ----Likely it is a 1990 model.

 

[hardwater fisherman]

These are some pictures I found.. You can see the different sizes of the carb bores.

 

[jimmwaller]

These are some pictures I found.. You can see the different sizes of the carb bores.

Ah yeah that's really helpful, thanks. If/when I need to get down to the carb I'll use that as a comparison. Thanks