9.9 to 15 hp conversion

Discussion in 'Boats and Motors' started by Gfunk, Dec 17, 2007.

  1. I recently bought a 2002 Mercury 9.9 4 stroke and was wondering what it would take to change it to a 15hp? I know the 2 strokes are pretty easy to change, but don't know about the 4 strokes. Is it as easy and changing the carb?


    just changeing the carb on the 2 stroke 9.9 to a 15 hp carb does not make it a true 15 hp there is more to it than that. but i dont know on the 4 strokes

  3. SwollenGoat

    SwollenGoat Scourge of Hoover

    From what I have read and been told this is a no-go with the 4 strokes. Guys have taken the trouble and replaced carbs, heads etc. and they just won't run right.
  4. It may have been easier to buy the 15hp and put 9.9 decals on it.:D
  5. Hey Gfunk why don't you buy a new 15 hp and sell me your old worn out 9.9 for a steal. i'm looking for one to put on a 22.6 fourwinns.:eek:
  6. I would be interested in finding out what to do w/ a 2 stroke 1971 9.5 HP to upgrade to a 15? It's an evinrude.
  7. Timmyv, I inquired into the conversion of an old 9.5 Johnson to a 15 hp a few years back. I asked Kenny Baker about it. Kennny is the best source of old outboard info and service in Columbus, IMO. He said it can't be done.
  8. Thanks for the info Bob...that kind of sucks! Oh well I guess I'll just continue to follow the rules at Hoover....