Merc horsepower increse

coopcafemgr

Cadet
Joined
Feb 27, 2011
Messages
9
I have a 1984 Merc 9.9 and a friend of mine said he had heard that you could change up to 15 horse power and I should as I use this on my 14 foot Northwoods alum. which I am finishing a new floor upgrade. Can someone give advice on this 9.9 to 15 Hp upgrade?:confused:
 

sxmerc

Petty Officer 1st Class
Joined
Jul 13, 2010
Messages
247
Re: Merc horsepower increse

I believe the only difference between the two is the jetting in the carb. Swap out the carb for a 15 horse carb.
 

boater1234

Master Chief Petty Officer
Joined
Jan 6, 2010
Messages
869
Re: Merc horsepower increse

I asked that question at my yamaha dealer as they have a brand new 9.9 yamaha 2stroke i may just buy and upgrade it to a 15 as it is the same powerhead.He told me the reeds and carb were the only difference from making it a 15hp.Probally the same with the merc.
 

jimg984

Chief Petty Officer
Joined
Jul 16, 2007
Messages
403
Re: Merc horsepower increse

wonder how customers can do what the mfg can't do lol
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,589
Re: Merc horsepower increse

The difference between a Merc 9.9 & 15 is :carb and exhaust porting of block. Also yours should be a 1986 model as they didnt make a 1984 9.9.
 
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