Is '96 9.9 same as '96 15 hp. Johnson?

[nickster]

I have my eye on a 1996 9.9 johnson. I would like to make this motor a 15hp motor. I'm not possitive but don't these motors have the same bore & stroke? So resulting in that all I would have to change is the jetting and the reed valves? Or is there more to change to make a 9.9 into a 15hp?<br /><br /> Thank You!<br /> Nickster

 

[Yepblaze]

Re: Is '96 9.9 same as '96 15 hp. Johnson?

Maybe the carb throat might be bigger too.

 

[nickster]

Re: Is '96 9.9 same as '96 15 hp. Johnson?

So Yepblaze would the only thing that I would have to do is change the intire carb then right. I've got some part catalogs. and the 9.9 and 15hp motors are in the same catalog. when looking through the part catalog I see that the 15hp cylinder and crankcase has a different part# than the 9.9 but it has the same part# for the crankshaft and piston assy. The big question is What do I need to do to make this 9.9 into a15hp? <br /><br /> Thank you!<br /> Nickster

 

[FlyBoyMark]

Re: Is '96 9.9 same as '96 15 hp. Johnson?

Newer models have several differences, tuned exhaust tube in the leg, ported differently and possibly in the model you have, different induction plates/manifold. Only the earlier models of this engine had a "carb only" difference. The early models wound up to 7000 RPM to get the 15 ponies and the mods on the newer 15 HP are to reduce the RPM to a more "quiet" and reliable motor. Better jus get a 15 HP.....