1971 Johnson 9.5 increase horsepower

[Ginsei9881]

Hello everyone,

I am new to the forums and not super familiar to boat engines. The engine I do have is magnificent and runs perfectly. I am just kind of hoping that I can get more speed out of her. With that I was wondering if there is a way of really getting more horsepower out of it. I have heard of some people swapping carbs but I can’t find anything like that for these engines. Anybody have any ideas?

 

[oldboat1]

Don't mess with an engine that runs perfectly. Make sure your hull is in good shape and load is balanced.

 

[racerone]

The carburetor is unique to the 9.5 HP model.------I suppose you could rework / adapt a 20 HP carburetor from various makes & models of motors to get a real hotrod.

 

[oldboat1]

Nah. Don't do that. If you like period motors, I really like the '57 or '58 18s, but you have a whole range of motors that will put bugs in your teeth if your boat will handle them.

 

[Ginsei9881]

That is really all I wanted to know (that the carb is unique to the 9.5s). I just wanted to scoot across these large Arkansas lakes a little faster but she gets me where I need to go. She’s just on a 1980 1436 flat bottom Jon boat anyway.

 

[iggyw1]

Might try a different ptched prop. Just make sure you stay withjin the max RPM's if you change the prop.

 

[Faztbullet]

Find a 15 hp and slap some 9.5 stickers on it...