Horse Power upgrade

[mfksea]

I have a 1991 Johnson 9.9hp Long shaft. I've heard the only difference between a 9.9 and a 15 is the carb. Is that all there is to it....switching to a 15's carburetor ?

 

[JB]

Re: Horse Power upgrade

On a few models, yes, only the carb is different.

On most models there are other differences.

Because the displacement is the same any increase in performance is small and not worth the cost of the hop-up.