1989 20 HP Johnson power upgraded to 25 HP for zero dollars

[Stefan]

[/quote]ok so starting in 85 the 20 and 25 had identical carburetors but for some reason or another they used different part numbers on the carbs and its the restricted intake on the 20 that makes the difference and not carb size.. hmmmmm....... well that makes sense to me, logical sense? no. but I understand now why my 1980 25 carb is the same exact size as the 35 carb and both have different numbers with the only difference being the 25 has a plastic ring inside the throat narrowing it to restrict the air flow a bit and to make the same powerhead as the 35 only produce 25hp. well Stefan sorry I drug this out and johnny25 into it to help me understand how and why but my hats off to ya for using your melon and getting 5 more HP out of your motor without spending a dime or whatever you use up there for coin. and thanks a lot johnny25 for going out of your way once again and helping a fella out!!!![/quote]

Shawnfish, this great info I am glad that we all looked into it... It does seem weird that OMC would restrict the motor like this. I mean why build a 20 HP motor when it is exactly the same as the 25 HP? Why not just offer a 25 HP?

I guess it's economies of scale, building motors with the same main components, but very subtle differences... Like car companies build vehicles on identical platforms to lower costs? Also, this way they can offer a wider range of motors to the consumer??

The extra power as a result of the mod is great.

 

[Johny25]

Well in 1985 the 20 and 25 had the exact same carb and part number 0395279 and the 20 and 25hp carried exact carb numbers up to 1988 at least. And I believe it continued after that it just becomes harder to trace the numbers.

All motor manufacturers use a single block casting to produce a couple or several different horse power ratings. This is for many reasons including cost and profit to the manufacturer, more HP options for consumer to get largest HP motor for their boat without going over CG transom tag regulations, and also fuel economy. It is the same with the 9.9hp that was made for so many years, all it was really is a de-tuned 15hp. And believe me there is a pretty noticeable increase in hours per gallon that your motor will burn by making HP modifications. I have done the 9.9 to 15hp conversion and the 25 to 30hp conversion and very easily could tell I was eating more fuel. But that is the price you pay for more ponies

Believe it or not some people don't care how fast their boat goes, just that it gets on plane and the fuel economy is good #-o and then there is the rest of us that think everything should and could go a little faster :mrgreen:

 

[Stefan]

Johny25 » Today, 13:51[/url]"]Well in 1985 the 20 and 25 had the exact same carb and part number 0395279 and the 20 and 25hp carried exact carb numbers up to 1988 at least. And I believe it continued after that it just becomes harder to trace the numbers.

All motor manufacturers use a single block casting to produce a couple or several different horse power ratings. This is for many reasons including cost and profit to the manufacturer, more HP options for consumer to get largest HP motor for their boat without going over CG transom tag regulations, and also fuel economy. It is the same with the 9.9hp that was made for so many years, all it was really is a de-tuned 15hp. And believe me there is a pretty noticeable increase in hours per gallon that your motor will burn by making HP modifications. I have done the 9.9 to 15hp conversion and the 25 to 30hp conversion and very easily could tell I was eating more fuel. But that is the price you pay for more ponies

Believe it or not some people don't care how fast their boat goes, just that it gets on plane and the fuel economy is good #-o and then there is the rest of us that think everything should and could go a little faster :mrgreen:

Some really great points. I think that the mod will save me fuel because now the boat planes, so the motor isn't working as hard to pushit along, plus it's not operating as much because I get to my destinations faster. For trolling I use a 6 HP evinrude as a kicker, which saves me a ton of fuel...

 

[Johny25]

Likely your motor was not running the correct recommended RPM if it wasn't getting your boat on plane. Being that you just bored the intake your fuel consumption should be better being you can plane now. I say get the intake and 30hp carb and go faster 8)

I made a post a couple years ago trying to justify that I was saving fuel by going faster. My theory was I got to my fishing spot faster and my motor was running for less time, hence the less fuel I burned :lol: Well I was wrong #-o I burned way more fuel cause I would go more places in a day and ran the motor more often so it really didn't save on anything

 

[Stefan]

Johny25 » 41 minutes ago[/url]"]Likely your motor was not running the correct recommended RPM if it wasn't getting your boat on plane. Being that you just bored the intake your fuel consumption should be better being you can plane now. I say get the intake and 30hp carb and go faster 8)

I made a post a couple years ago trying to justify that I was saving fuel by going faster. My theory was I got to my fishing spot faster and my motor was running for less time, hence the less fuel I burned :lol: Well I was wrong #-o I burned way more fuel cause I would go more places in a day and ran the motor more often so it really didn't save on anything

LOL for real, that is too funny. The first weekend I had it out with the mod, I found myself booting around just for the sake of booting around because I was so happy the motor was working so well. I think you're right, I'll end up using more fuel now because I can... That being said, I agree with the notion of getting the 30 HP carb and intake. I can only imagine how fast the fishing machine would go with those parts, plus my 6 hp started and full throttle at the same time!

Thanks so much for all of your input on this threat and the knowledge you've shared on other threads. I've read through your mod extensively.

 

[shawnfish]

Likely your motor was not running the correct recommended RPM if it wasn't getting your boat on plane. Being that you just bored the intake your fuel consumption should be better being you can plane now. I say get the intake and 30hp carb and go faster 8)

I made a post a couple years ago trying to justify that I was saving fuel by going faster. My theory was I got to my fishing spot faster and my motor was running for less time, hence the less fuel I burned :lol: Well I was wrong #-o I burned way more fuel cause I would go more places in a day and ran the motor more often so it really didn't save on anything

when I first read Stefan's post the first time prop change came to mind but kept reading and he had already tore his motor apart and got after it. and im with the I wanna be going down the lake with my hair on fire crowd and if I have to spend a little more on fuel really its not that big of a deal because 90% of the fishing I do is on lakes no bigger than 200 or so acres. I love these threads like yours and johnny25's especially because they are done on old OMC's and im sure you guys have seen my posts about the OMC small outboards (40hp and under) being the best built most reliable and user friendly outboards ever built and I would put them up against any brand new outboard on the market today id also bet that our pre 90's johnny/rudes will still be running after the ones being built today are in the scrap heap as long as they have just the very basic maintenance stuff kept up on them. I also believe what ive heard from some mechanics and a couple very knowledgeable guys right here on this site that from the late 50's until the 90's that these motors were over engineered and it makes sense because theres more older OMC's still making wakes than there are all of the other older OB's combined. that's all my grandpa would buy was OMC and my 1980 was the last brand new OB he bought and I inherited it so to speak and for almost 34 yrs old that motor has never left me in the breach besides when the operator might have forgot to put fuel in it once or twice lol! so yeah I like OMC's and defend them like they are my little sister surrounded by teenage boys!

 

[Stefan]

Shawnfish, you are absolutely right, I think that the OMC engines from the 70's and 80's are over engineered. I spoke to a guy who worked at the OMC factory where my engine was made, just east of where i live in Peterborough Canada, and he told me that the engines are rock solid. These things are tanks, they go and go and go with just regular maintenance.

I have a 1989 Johnson 20 HP, 1972 Johnson 20 HP (anniversary edition) I scored on a trade for an old tattered portable ice hut I didn't use anymore and a 1973 6 HP Evinrude Fisherman. All amazing engines that run great.

The only issue I worry about is ethanol killing the seals and lines, but I treat the gas with stabilizer, so apparently this is supposed to help. This winter I hope to rebuild the carbs on all three engines and if you guys don't mind I might be drawing on you for some help if I encounter problems. Also hoping to clean up the engines, paint them up and order decal kits for all of them...

 

[Plasticmotif]

I had it reinstalled running after boring the intake.. I had a small leak from the float nipple. Tightened it up and it broke right off. Doh!

So, it's apart again today. I got the broken nipple out. New ones at my marine shop. Pick it up tomorrow.

Well see how it goes after that!

 

[shawnfish]

Johny25 » Today, 10:28[/url]"]Ok I skimmed the thread real quick as I am in a hurry today but will try and give my 2 cents. Yes the only difference in 20 and 25hp in this year is the restricted intake design. The 20 and 25hp starting in 1985 had identical carburetors. I believe I covered this in my 20/25hp to 30hp conversion thread but maybe I didn't? We could debate all day whether it actually gives an extra 5hp by boring the intake out but unless someone has a dyno for outboards we may never know. the theory is there though.....more air in should make more HP. I will also say that I owned an 85' 20hp and it did not seem to run as smooth as my 85' 30hp or my 88' 25hp and this I suspect was because of the restricted intake. The motor really seemed to want more air.

Now a little history on the 20hp.......the 20hp motors that we are talking about came out in 1985. The same year OMC started prop rating the HP of there motors. Before that the 20hp was last made in 73' in the smaller 22ci block, and only the johnson logo or tag was released in the 20hp. Evinrude never had the 20hp tag until 1985....they were labeled 18hp pre 74' I believe although I suspect motors were identical. Likely a marketing ploy of some sort. Also in 1984 the 35hp was discontinued and became the 30hp of 1985. The 35 was brought back for one year in 1987 but it was a restricted 40/50 HP motor. And then again somewhere in the 90's I believe it came back but now I am at the limits of my memory without researching again.

But in short......in 1985 the 20hp came out and had a restricted intake, and only that is what separated it from the 25 for several years. I'm not sure but I believe at some point there was more than just the intake difference in the 20 and 25 but cannot remember when it was? In the 90's I believe

they brought back the 35hp in 96 but it was a 3cyl not a 2cyl and was still in production in 2002 and maybe longer but I didn't want to read anymore tonight because im tired. they also made a 35hp jet from 93-97 and they made a 20hp in 97 for one year but like I said I made it to 2002 and wanted to post this before I crash for the night... I have a awesome site packed full of info for outboards, stern drives etc... if anyone would like it....

 

[Stefan]

Plasticmotif » Today, 21:26[/url]"]I had it reinstalled running after boring the intake.. I had a small leak from the float nipple. Tightened it up and it broke right off. Doh!

So, it's apart again today. I got the broken nipple out. New ones at my marine shop. Pick it up tomorrow.

Well see how it goes after that!

Let us know the results Mac, I am really looking forward to reading if it makes a big difference on your boat...

 

[Stefan]

they brought back the 35hp in 96 but it was a 3cyl not a 2cyl and was still in production in 2002 and maybe longer but I didn't want to read anymore tonight because im tired. they also made a 35hp jet from 93-97 and they made a 20hp in 97 for one year but like I said I made it to 2002 and wanted to post this before I crash for the night... I have a awesome site packed full of info for outboards, stern drives etc... if anyone would like it....[/quote]


that would be great Shawnfish, could you post the link?

 

[shawnfish]

im computer challenged so I will just type it in https://boatinfo.no/lib/library.html

manuals, brochures and other technical documents from the last 100yrs. I think I got it off this site but cant remember.

rebuilding your carbs is probably a lot easier than you think if you have not done it before and like you said theres help here. you wont find factory decals that are still available for your motors except maybe the 90 at least not down here south of the border. theres a guy who makes the best factory reproduction decal sets that ive ever seen and actually I couldn't tell they were not factory and are hands over fists better than the ones on ebay and other sites in regards to color match and quality material and if you want he will make you the factory decals with different colors if that's what you want or have them modified a certain way if you wanna go that route almost every set ive seen on the site run 75.00 to 110.00 dollars for our HP size anyways its NY.MARINE and since your up in Canada I have a couple questions for you. what does the Canada derated in your model number mean? and also I was doing my daily screen shopping on ebay and saw a Johnson cowling that said TNT on it with like a yellowish horizontal stripe that looks factory to me and in the description for the seller it said "from Canada" have you seen one like this up there

 

[Charger25]

This whole thread is a prime example of why I love this site. Useful exchange of Ideas, information, opinions and knowledge.
I humbly appalled you all. =D> =D> =D> And thanks for the boatinfo link shawnfish.

 

[Stefan]

shawnfish » Today, 05:38[/url]"]im computer challenged so I will just type it in https://boatinfo.no/lib/library.html

manuals, brochures and other technical documents from the last 100yrs. I think I got it off this site but cant remember.

rebuilding your carbs is probably a lot easier than you think if you have not done it before and like you said theres help here. you wont find factory decals that are still available for your motors except maybe the 90 at least not down here south of the border. theres a guy who makes the best factory reproduction decal sets that ive ever seen and actually I couldn't tell they were not factory and are hands over fists better than the ones on ebay and other sites in regards to color match and quality material and if you want he will make you the factory decals with different colors if that's what you want or have them modified a certain way if you wanna go that route almost every set ive seen on the site run 75.00 to 110.00 dollars for our HP size anyways its NY.MARINE and since your up in Canada I have a couple questions for you. what does the Canada derated in your model number mean? and also I was doing my daily screen shopping on ebay and saw a Johnson cowling that said TNT on it with like a yellowish horizontal stripe that looks factory to me and in the description for the seller it said "from Canada" have you seen one like this up there

Shawnfish, that link you posted is a wealth of information, thank you so much! I've booked marked it and will look through that extensively.

Thanks for the decals source, I've got a great source just north of Toronto that custom prints them as well for a pretty reasonable price. It's amazing what new decals will do for the look of the engine. But regarding your two questions, about Canada de-rated in the model number - I'm not sure what you mean, can you post the model # that you are talking about.... and the TNT emblem on the cowling of the motor; I have never seen this before, so I really don't know to be honest with you.. . but if you post the link for what you saw that might yield some answers...

 

[Plasticmotif]

Got it roughed in. Was backfiring out of the water when in neutral. Hopefully it's just bad gas and no back pressure on the exhaust.

I got it registered today. Will be taking her out tomorrow see if I can get her to plane!

 

[shawnfish]

Stefan » Yesterday, 07:48[/url]"]

shawnfish » Today, 05:38[/url]"]im computer challenged so I will just type it in https://boatinfo.no/lib/library.html

manuals, brochures and other technical documents from the last 100yrs. I think I got it off this site but cant remember.

rebuilding your carbs is probably a lot easier than you think if you have not done it before and like you said theres help here. you wont find factory decals that are still available for your motors except maybe the 90 at least not down here south of the border. theres a guy who makes the best factory reproduction decal sets that ive ever seen and actually I couldn't tell they were not factory and are hands over fists better than the ones on ebay and other sites in regards to color match and quality material and if you want he will make you the factory decals with different colors if that's what you want or have them modified a certain way if you wanna go that route almost every set ive seen on the site run 75.00 to 110.00 dollars for our HP size anyways its NY.MARINE and since your up in Canada I have a couple questions for you. what does the Canada derated in your model number mean? and also I was doing my daily screen shopping on ebay and saw a Johnson cowling that said TNT on it with like a yellowish horizontal stripe that looks factory to me and in the description for the seller it said "from Canada" have you seen one like this up there

ok your model number CJ20CRCEM C=CANADA J=Johnson 20=HP CR=CANADA DERATED CE=89 M=PRODUCTION RUN


not sure if your familiar with the year code designation or model code designation that they started using in 1980 but if your not you can find it at evinrude,brp marineengines... and you use that to decipher the model number for year built and options like long or short shaft, rope or electric start, tiller or remote etc....it has other countries listed as derated too and I wonder if its something to do with their emission standards or something cuz that's all I can think of.....
Shawnfish, that link you posted is a wealth of information, thank you so much! I've booked marked it and will look through that extensively.

Thanks for the decals source, I've got a great source just north of Toronto that custom prints them as well for a pretty reasonable price. It's amazing what new decals will do for the look of the engine. But regarding your two questions, about Canada de-rated in the model number - I'm not sure what you mean, can you post the model # that you are talking about.... and the TNT emblem on the cowling of the motor; I have never seen this before, so I really don't know to be honest with you.. . but if you post the link for what you saw that might yield some answers...

theres a pic of the hood. if I didn't tell you already marineengine.com has NOS factory decals for your motor for 45.00 and if I was you id jump all over that deal, gotta be cheaper than custom printed decals....

 

[shawnfish]

it looks factory to me the way the stripe looks like it goes behind that tag/emblem on the back.....

 

[longshot]

I just did something very similar to this on my 2003 tohatsu. It needed the carb overhauled and I discovered the 9.9/15/18 were all the same except for the carbs. So I ordered a new 18 carb runs great in the tank I will be trying it out at the lake in the morning

 

[Stefan]

longshot » Today, 09:55[/url]"]I just did something very similar to this on my 2003 tohatsu. It needed the carb overhauled and I discovered the 9.9/15/18 were all the same except for the carbs. So I ordered a new 18 carb runs great in the tank I will be trying it out at the lake in the morning

How did it go? did you notice a big diference in speed and power??

 

[Stefan]

Plasticmotif » Yesterday, 21:19[/url]"]Got it roughed in. Was backfiring out of the water when in neutral. Hopefully it's just bad gas and no back pressure on the exhaust.

I got it registered today. Will be taking her out tomorrow see if I can get her to plane!

Platcimotif, congrats on getting her registered??? How did it go today? Did you notice differnces? Any suggestions you might be able to offer??

I hope things went awesome!