Can A Yamaha 9.9 Be Made Into A 15 Hp?

[swordfish25]

The 9.9 seems to be the same engine specs as the 15 hp 2 stroke. Can this be done by changing the carb., and maybe the exhaust covers? Thinking about buying a new 15 [ 2 ] stroke, and might be cheaper to get a 9.9 and convert it. Any ideas on this, if so what part numbers, and what price?

 

[swordfish25]

Re: Can A Yamaha 9.9 Be Made Into A 15 Hp?

bump

 

[rodbolt]

Re: Can A Yamaha 9.9 Be Made Into A 15 Hp?

without researching all of it again, change the reed block.
most the 9.9's used a two reed block.
the 15's used 3.
but with no year model I cant say more other than if its poist 1998its illegal

 

[nocab68]

Re: Can A Yamaha 9.9 Be Made Into A 15 Hp?

Absolutely- I have a 1988 model 9.9SG- 2 Stroke. This is accomplished by replacing the reed valve assembly and carburetor with the 15 HP parts. You must replace the carb rather than jets only as the 9.9 carb barrel is 15mm and the 15 HP carb barrel is 19mm to provide more airflow to the engine. You will read the performance increase is negligable however the perfromance will alow you to increase your prop pitch and maintain WOT. I gaines significant hole shot and 7 mph on a 16' riverhawk by doing this. Well worth the investment of $210. Sell your 9.9 carb on ebay, and offset the outlay by a few bucks.

 

[rodbolt]

Re: Can A Yamaha 9.9 Be Made Into A 15 Hp?

there again it DEPENDS on the year model.
some years the 9.9 and 15 used the same carb just a different reed box assy.

 

[swordfish25]

Re: Can A Yamaha 9.9 Be Made Into A 15 Hp?

Thanks for the threads. I decided to bite the bullet and get a new 15 two stroke, and glad I did. This thing runs great, and runs on fumes.