Turning a 9.9hp into a 15hp outboard. Actual GPS results. Is it worth it?

[@mikep303]

That's one way to make your johnson bigger😊

[@dentalnovember]

I would love to have this motor. These gems are tough to come by.

[@M4ttsStuff]

same

[@Reeldrivenoutdoors]

I have this motor and can confirm it’s a fuggin work horse and I dk if I’ll ever sell it 🤙🏼

[@ScreamAndFly]

I have a 2005 9.9 Johnson that I bought new, and it’s still in the box, never run!

[@dentalnovember]

@ScreamAndFly Want to sell it to me?

[@shawn467]

I had a late 70's 9.9 that I changed to a 15 and in addition to a different carb, there was also a spacer that allowed the reed valves to open more. It was a great running motor until I let a friend drive the boat. He made a sharp turn at high speed and the motor tore off of the transom and went to the bottom of the creek. It's still there if anybody wants it!

[@M4ttsStuff]

bet

[@davidmann4533]

If it was mounted correctly it would not fall off not your friends fault yours

[@danblanchard9145]

Did you swap out the prop as well to account for the extra horsepower? I’m thinking that a 33% increase in horsepower would require more pitch at the same RPM.

[@coreyok123]

Huhhh?

[@Tazmonster]

What does the knob on the handle , I try to play with mine but don't see waht it does?? Thanks, and good video

[@dozerfarms]

Are the props on the 9.9 and 15 the same? Could you run a steeper pitch with the 15 for more speed now with the added power?

[@jnljnl8485]

What's next? Cut the cylinder to set squish and some porting? 😂

[@danielstark8258]

Stroker

[@danielstark8258]

Fastest my 9.9 has done is 22mph, with no wind. Debating if it’s worth it or not. The 15hp also seems to have a larger throttle valve. Still debating wether to look for a parts motor or if I should just have it machined

[@outboardfun3353]

You have also change to the turned exhaust tube that 15hp has. If you put more gas in you have to gas more exhaust out also to be 15hp

[@DCFloridasport]

dont ever let that old girl go!

[@ScottUnangst]

i have a 1998 johnson 9.9 and 15hp models. Both vary low hour motors. they both will idle down to almost nothing. the 15 screams top end but seems to stumble mid range were the 9.9 remains smooth. i think the cylinder porting are different between the two. maybe thats why i only see 9.9's on sailboats

[@ScreamAndFly]

Porting is identical. Differences between the 9.9 and 15 vary depending on year but in most cases it’s the carb, the exhaust tube, and the reed block spacers added to the 15. Low end torque is identical between the two so that’s why the 9.9 was more common on sailboats. There was also a dedicated long shaft sail version of the 9.9.

[@colinmcalister8704]

Check parts diagrams for both. Reeds and exhaust may differ.

[@philbo65]

Would this work with an old 9.5?

[@gioscervelo]

That's about right. My Evenrude went from 9.9 hp 30 kph 15 hp 35 kph. My 15hp Nissan goes 40 kph

[@jadenporter3975]

Where did you find a carb I have same year motor I’d love to do the swap but can’t find a carb

[@allyoucancatchoutdoors6898]

Yea where can we get the carb from?

[@07slowbalt]

Kinda surprised me how well that thing moves for such a small motor

[@mikeeiben3430]

Ill it troll as nice with the larger carburetor?

[@ct1762]

no definitely not!

[@rafawojtaszczyk1409]

what fuel mixture for this engine is 1:100 or 1:50

[@coreyok123]

1:50

[@Jerold-bu3ul]

If this just worked on all johnsons.

[@ericbullock3188]

i was told you can do the same with a mercury .