scott kittredge
Member
i think some one told me that i could make my 05 johnson 2 stroke 9.9 hp into a 15 hp by rejetting the carb. is that true?? thanks scott
to 15 hp
- Thread starter scott kittredge
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Ron Schuna
Well-known member
Will is work with a 70's 9.5 Evinrude? I'd love to hop the one I have up....my Huff Box would fly....(goes good as is but more power........oh yeah)
Howard, Ron, and others,
I was always under the impression that besides the carb jetting, the intake reeds used a spacer and the inner exhaust sleeve needed swapped out as well. Maybe that changed by model year because I'm thinking of a late '70's model year.
In fact if I remember correctly I tried just changing the jet in mine and all I accomplished was to burn more fuel. Never noticed a power increase. That is when I was told I'd have to add the spacer behind the reeds(to allow them to open father) and swap out the exhaust.
Maybe Tom Scholberg will chime in with his knowledge.
I was always under the impression that besides the carb jetting, the intake reeds used a spacer and the inner exhaust sleeve needed swapped out as well. Maybe that changed by model year because I'm thinking of a late '70's model year.
In fact if I remember correctly I tried just changing the jet in mine and all I accomplished was to burn more fuel. Never noticed a power increase. That is when I was told I'd have to add the spacer behind the reeds(to allow them to open father) and swap out the exhaust.
Maybe Tom Scholberg will chime in with his knowledge.
jeff minnick
Active member
not sure what year my old one was but i changed carb and it worked great
Tom Scholberg
Well-known member
The only way to answer this question is to go through the parts breakdown and compare part numbers. Some of the changes being discussed here are possible and some are too expensive with new parts. Ron, the 9.5 is a whole different motor from a 15, I'm not even sure there was a 15 in those years. The 9.9 is the same family of motor as the 15 much like the 25/35 family. I have checked the #s on some of these and it is possible BUT when you check the prices sometimes it doesn't make sense. Sometimes just a jet change will do it sometimes it takes a whole new carb. The other part that is needed sometimes is the exhaust tuner which can be really a pricey part. Used parts can bring this changeover back into line. I have had acess to dealer parts breakdowns to check this out but I think there is online references available (Dave, you out there?). OMC motors are kinda like the small block Chevies for parts interchangability, some work some don't. Good Luck and keep us informed. I have a bunch of "basket" 9.9s and 15s that will be going back together in the future so there will be more research to be done.
Tom,
The exhaust tuner was required in my case and even back then it was costly. I opted to stay with the 9.9 rather than convert. As mentioned earlier I tried just swapping the jet and that was not enough for my particular engine.
Later I will try to post a link to the OMC on-line schematics, they are quite good as long as you have an engine serial number for the engine parts you are considering.
Fellas,
Here is a link to a very handy schematic and parts catalog for those OMC outboard engines. You need to start on the first page and go from there based on model year and model number till you get to your specific engine. From there it further breaks down into part groupings.
Here is a link to a very handy schematic and parts catalog for those OMC outboard engines. You need to start on the first page and go from there based on model year and model number till you get to your specific engine. From there it further breaks down into part groupings.
John Pawelec
Member
Check this link out. http://www.leeroysramblings.com/OMC_9.9_1993.htm on the bottom of the page is what you are looking for.
Jpaw
Jpaw
Howard,
It has been quite some time since I looked into this and it may well be that either I was misinformed or my memory is lacking. At any rate, those interested can cross reference the part numbers as they see fit.
The spacer was only a thin shim which installed between the reed and the backing fingers which limit the max. bending of the reeds. I'm thinking it was only about .030 thick. This allowed the reeds to flex open just a wee bit more but not enough more that they would flex too much and break. Then again the spacer may have been a backyard racers modification. I remember doing the same thing to go-kart engines back in the day.
PS. I read thru some of the material in the link provided above by John and it seems the spacer I referred to was a .015 thick spacer. The author also mentions that the newer versions of the 9.9/15 are quite a bit different and redesigned from the older models that I am most familiar with.
It has been quite some time since I looked into this and it may well be that either I was misinformed or my memory is lacking. At any rate, those interested can cross reference the part numbers as they see fit.
The spacer was only a thin shim which installed between the reed and the backing fingers which limit the max. bending of the reeds. I'm thinking it was only about .030 thick. This allowed the reeds to flex open just a wee bit more but not enough more that they would flex too much and break. Then again the spacer may have been a backyard racers modification. I remember doing the same thing to go-kart engines back in the day.
PS. I read thru some of the material in the link provided above by John and it seems the spacer I referred to was a .015 thick spacer. The author also mentions that the newer versions of the 9.9/15 are quite a bit different and redesigned from the older models that I am most familiar with.
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