Hey guys. I heard that you can make a 9.9 into a 15hp a few different ways. The reason I'm asking is because I'd like a little more push without buying another motor. I bought a 1974 9.9 Johnson before I bought a boat cause it was a great deal. Bought a 15.5' tinny later on. Wasn't planning on a boat that big but again it was a great deal. I'm getting my boaters card in the next week so I am not trying to cheat the gov.t (Lord knows they deserve it). Some guys are saying it's just the carb that is different. The 15hp carb allows more air and fuel in thus creating higher rpm. From the research I did on parts, it seems that both the 9.9 and 15 have all the same block, piston, rings, etc. The other method I hear is to change the wieghts on the flywheel. Has anyone here done a successful conversion or can vouch for one? Any help or suggestions would be greatly appreciated.
Thanks people,
Curt