Convert Evinrude 9.9 into a 15 horse

1/29/15 @ 11:21 AM
ORIGINAL POST
fishinfool1
fishinfool1
USER since 3/14/10
I have a 1978 evinrude 9.9 that runs just fine. I have it on a 12' Sea Nymph Aluminum boat. I heard that just by changing out the carburetor I can convert my 9.9 into a 15 H.P. Anybody try this and what do you think. thanks
Edited on 1/29/15 11:22 AM
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Displaying 1 to 10 of 12 Posts
4/5/15 @ 6:08 PM
fillet-o-carp
fillet-o-carp
USER since 12/1/12
Rob Look at the part list for your motor and a 9.9 and see what is different . I am not sure . If the piston and rod, crank are the same then you should be able to with just a carb , maybe even just a jet in the carb if your real lucky

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4/5/15 @ 3:20 PM
Robbollio
Robbollio
USER since 10/17/04
Can i make my 4.5 evinrudw into a 9.9? I've actually heard you can do that to...

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4/5/15 @ 2:13 PM
fillet-o-carp
fillet-o-carp
USER since 12/1/12
I got a new 9.9 and just ordered a carb for a 15 horse . I looked thru every part on the parts list and it the only part with a different number of the two and the bore and stroke are the same so they are identical motors besides carb . I only thought of doing this because when I took my cover off it was written 9.9 on the carb so I figured that it was writin on there so they wouldn't put it on the 15 horse . Lol so basically I saved some money buy just ordering the 15 horse carb for 105 bucks

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3/3/15 @ 8:32 PM
Tunaboy
Tunaboy
USER since 1/13/15
I used to have a 9.9 and sold it and bought a 15hp. There is a big performance difference.

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2/10/15 @ 11:29 AM
Highthrust
Highthrust
MEMBER since 1/21/13
I would not bother make the change. The 15 only gets more power by running higher rpm. If you can't get the rpm now you will not get any more speed with the update. Typically the speed difference and acceleration is unmeasurable between the 9.9 and 15.

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1/30/15 @ 7:31 AM
centralwiwalleyeslayer2
centralwiwalleyeslayer2
USER since 2/15/10
i have a 30hp on my 14 foot boat could of went as big as 40 on it. and its a 74

Edited on 1/30/15 7:31 AM
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1/29/15 @ 6:29 PM
wskiph
wskiph
USER since 9/3/11
I HAVE 73 Merc 9.8 3 adults and 1 child,,14ft Aluma craft and it will go on plane,,not fast but you get to where you need to go,,,,don't waste yr money on old motor,,,if it runs good enjoy it

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1/29/15 @ 5:56 PM
Horble
Horble
USER since 4/11/08
A carb assembly from a '78 15 should bolt right up and be fine. I believe the exhaust tubes for the late '70's 9.9-15 OB's were the same. Finding a good carb assembly for that year is the challenge.

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1/29/15 @ 4:59 PM
fishinfool1
fishinfool1
USER since 3/14/10
Wet-Net, I have the 9.9 motor on a 12' now and its fine on the lakes with me and the wife, but I also have a 14'boat that is obviously longer and wider and will hold a third or fourth person/kids, the 9.9 just doesn't move it very well and I want to be able to run it upstream on the Menominee River without worry. More horsepower for bigger boat is the main reason for the possible conversion.

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1/29/15 @ 3:23 PM
fltlndr
fltlndr
USER since 12/25/02
I believe it's the carb and the heads.

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Displaying 1 to 10 of 12 Posts