1992 yamaha 4 stroke 9.9 to 15 hp

[nogimmies]

Want to convert 1992 yamaha 9.9 to 15 hp if possible
I can not find a 15 carb for that year
Can I modify a 9.9 carb to make it run like a 15 hp
If so what drill sizes would work to make the modification to the jets.
Do I need another intake manifold or would the 9.9 suffice.
nogimmies

 

[apogee]

9.9 4-stroke misfire

9.9 4-stroke misfire

My 1998 Yam 9.9 4-stroke starts and idles fine. However when I put it into gear and increase the revs a little there is misfiring, sometimes more, sometimes less and the oil light flickers. Increase the revs further and all is again well.
I have stripped and cleaned the carb. Could this be a fault with the oil pressure switch? (oil level ok) Or what? Any thoughts would be appreciated!