convert 2004 yamaha four stroke 9.9 hp to 15hp?

cmarsh33 · #1 August 2nd, 2009, 09:50 AM

hey i have been trying to find out the FACTS about converting a 2004 yamaha 9.9 four stroke to a 15 hp. I have heard several things such as carb change, reeds, exhaust. If any outboard mechanics have info on this topic i would be greatly appreciate finding out if it is possible on a 2004 four stroke.

Mackerel King · #2 September 11th, 2009, 02:44 AM

I have a similar (2005) 9.9 and am wondering the same thing. Searching through the archives I see a lot of talk of 2 strokes or general statements about why or why not you should try this but no definitive answers as to what parts are required for the 4.

Mackerel King · #3 September 22nd, 2009, 04:06 AM

Anything different other than the carb on this year?

Mackerel King · #4 September 27th, 2009, 12:02 AM

This 9.9 is yearning to be a 15. He just needs a wee bit of help...

Silvertip · #5 September 27th, 2009, 12:33 AM

No reeds on a four stroke. That's what the valves are for.

Mackerel King · #6 September 27th, 2009, 02:00 PM

I am aware of that and not the OP. When I look at the parts diagram I see no difference other than the carb. Anyone out there know if there are any other differences for 2005 9.9 4 stroke.