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Converting 9.9HP to 15HP by changing carberuter?

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  • Converting 9.9HP to 15HP by changing carberuter?

    I have a 1998 Johnson 4-stroke 305cc 9.9HP engine. It looks like everything on this engine is identical with the 305cc 15HP engine except the carberuter. Can I but a new carberuter and upgrade my 9.9 to 15HP?
    Where can I buy it? I've only been finding careruter kits instead of the complete carberuter.


  • #2
    Re: Converting 9.9HP to 15HP by changing carberuter?

    Hi Everybody,

    I finally figured out how to search this forum in a way that returned less than 100 posts to my question (ten of which applied).

    I have the "answers" to my question, from most frequest to least:
    (1) Sell my 9.9 and buy what I want/need.
    (2) Yes, its possible, but probably requires some exhuast modifications as well.
    (3) Review ALL part numbers between to two models in a actual shop manual, then decide if it makes sense.



    • #3
      Re: Converting 9.9HP to 15HP by changing carberuter?

      This has been talked about til the cows come home as you have seen in your search. Someone just changed out a 15 to a 9.9 carb this week and I asked if they noticed any appreciable difference in power and they haven't responded. Someone ( a while back) said they were going to do a more thorough comparison and I never saw anything re: results. I think get a 15 if you want a 15 is probably the right thing to do. Rick.