15 HP Merc v. 25 HP Johnson and Price Check

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bigredxlt

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Looking for advice on whether or not to bump up the size of my motor on my 15 ft grumman jon.

I currently have a 2 stroke 15 hp merc which runs great, not sure what the year is seems to be late 90s I honestly don't know though.

cd051315-c071-498d-b85a-6a7c6465f2f7_zpsc5b1df67.jpg


I found an '83 2 stroke 25 hp Johnson w/ controls on craigslist within driving distance. The seller is asking $900. The guy claims it runs great and that he's had it for 20 years.

8a6a15a8-56f9-4447-8e47-7bb532eb22b8_zpsf001866a.jpg


So I guess I have 4 questions. Answers to any of them would be appreciated. Thanks

1) What do you think is a good price to offer for the Johnson?
2) Do you think it is worth it to upgrade for the extra HP even though it is an older motor?
3) Can anybody tell what year that merc is?
4) How much do you think I could sell the merc for if I did end up buying the Johnson?
 
This past fall I sold a 1994 15hp Mariner tiller for $800. Looked pretty similar to your motor only grey. I upgraded to a 1993 25hp Mariner and it has much more power. I have it on a 1654 Mod-V that is fully decked with .75" plywood and it will push the boat with myself and one other guy 24mph. I was lucky to get 14-15 out of the 15hp.
 
your motor doesnt have a tiller? out west that would be a hard sell. the two motors are worth about the same, so im guessing your motor would fetch a high of 700 and 500 average.

that 25 hp seems a little on the high side. not really a great year for the johnyrude, later years i.e. have the flow through exhaust so prop selection is better. i personally like johnsons over merc, but that is just me.

agree that first choice would be a yamaha, with the johnnyrude close second. there will be a huge difference in speed and planning but fuel consumption will be about twice as much as now i.e. 15hp/1.5 gph vs 25hp/2.5 gph.

dino
 
I would not do it. The 15 runs just as strong as the Johnson 25. I have had 3 of the 15 Mercs and 2 of the 25 johnsons. The 15's just ran as hard as the Johnson. Plus it is way better on gas.
 
[url=https://www.tinboats.net/forum/viewtopic.php?p=341452#p341452 said:
tomme boy » 14 minutes ago[/url]"]I would not do it. The 15 runs just as strong as the Johnson 25. I have had 3 of the 15 Mercs and 2 of the 25 johnsons. The 15's just ran as hard as the Johnson. Plus it is way better on gas.

Wanna' bet on that?? If so make sure and bring a briefcase full of money for me. Would love to take it from you.
Saying a 15 will run with a 25 is a mouthful around here.
Do you actually think a manufacturer would allow an engine having an additional 10hp provide only enough performance to equal a rival's smaller engine? You don't think dealers would have alerted the manufacturer should this have been the case?
When you make a statement like that on here be prepared to back it up with hard facts.
We are waiting................................
 
I think he might be referring to the difference in the age of motors in comparison. The merc is over 10 years newer and rated after manufacturers started hp rating at the prop. So we are talking about a 7 hp increase which really doesn't seem to justify buying and older potentially less reliable motor that is worse on gas. If that's what he was getting at I think he's right. If it ain't broke don't fix it. Maybe down the road I'll upgrade to a newer 25 hp when the right deal comes around
 
The 25s were almost all conservatively rated. When the rating came out in 1984 engines could be rated within 10% (either more or less) horsepower. OMC didn't change anything to achieve it on those engines. They were very strong engines. Thru-hub or not they will outrun a 15 on any given day.
 
Pappy, you're probably right. A more powerful motor will outrun a weaker one. The question just comes down to whether or not the gain in power is worth the change gph, the hassle, and the price all for an older motor. At that price point there's no way it makes sense. Now if I could get my hands on an 85 or newer Johnson 25 for a decent price then mod it up to 30 hp I think that the hassle and increase in gas consumption would definitely be worthwhile.

Thanks for all the advice guys. it definitely helped me out.
 
It will probably be pretty tough for me to find one with controls as my boat has a console that I don't want to get rid of any time soon. I guess that's why I was so interested in the one I posted
 
The Merc 6,8,and 9.9hp are all 209cc engines. The 15hp Merc is 262cc. The Merc 18,20,25hp engines are 400cc. The Johnson Evinrude 20,25,28,30,35hp are 521cc engines. All of these engine are designed and tuned by factory engineers as marine 2strokes. Nobody left any horsepower "on the table". These engineers were operating in competitive market environment with big design and testing budgets. Now, years later, if you buy a 15 or a 25, that's what you get...depending on condition. A nice fresh 15hp with low use might outrun a rattly old 25 with a million hours on it. A good 25 will pull a tube and still outrun a good 15.
 
Just something to add. The Johnson's horsepower is rated from the head if it is actually an 83. All 1985 and newer outboard motors horsepower is rated off of the prop. Your Mercury looks like a mid to late 90's model. I don't really know that if this would be enough of a difference for your Mercury to equal or exceed the Johnson's stated horsepower.
 
Pappy, I built this boat for duck hunting. I had 2 different 15 hp Mercs I ran. One was a 2004 and the other was a 2002. Both bought new by me. I also had a 2004 25 Johnson, I bought this new also. I also had a 1448 Alumacraft with no center seat. The wood boat ran 32 mph on 2 different GPS's. The Flat boat ran 28 mph. This is with the 15 Merc's.

The same boats with the Johnson ran 27 with the wood boat and 24 with the flat. All motors had SS props. You are NOT the all knowing you think you are on this board.



This was before I bought the SS prop.

 
Tomme B?

I got no horse in this race, but Pappy is a highly regarded and well-respected member of the forum, who is very generous with his substantial knowledge.

If you have experiences that contradict his suggestions, perhaps it would be well to end your post at describing those experiences, and leaving the editorial comment off your post.

As it stands, it adds nothing in the way of information, and reflects poorly on the poster.

Best wishes.
 
I am no authority on the laws of physics where you live. Where I live, no stock 15 Mercury, Evinrude, Yamaha(or anything else) EVER outran a stock 25 Mercury, Evinrude, Yamaha(or anything else)... back-to-back on the same boat. The possible mis-perceptions of this could result from: improper setup, prop selection, mechanical problem, or putting up a longshaft engine against a shortshaft.

I put a 25 Johnson a 12 Mirrocraft once that jumped up and down so violently that there was no way to stay on the throttle. It was nice with a 10 or 15hp. Boats can work well up to certain speeds and then the bottom starts flexing. Boats are sometimes barely enough for one engine and overwhelmed by a larger one.

If the GPS moves inside the boat while taking a reading, it can be way off.


Hundreds of hours 'GPSing' different aluminum boats, different engines, different props, different air tempeatures, different water conditions, different trim settings, different mounting heights, different load placement, etc.etc., has taught me one thing: There is no free lunch.

Finding a 15hp that runs with all the 25s...well that would certainly be a free lunch.
 
Read a lot of posts/replies from pappy and he never came across as as "all knowing" just real passionate about O.M.C. Forget about brand
loyalty it comes down to finding a motor thats in good shape.I would recommend a 20hp mercury from the 90s-2004 good power and excellent fuel economy.It is a real shame you can't buy a brand new 2-stroke(carbed) I think I'll start a post on that very subject.
 
Might be interesting. :popcorn:

Not sure how moving the gps in the boat throws it way off unless you lose signal. That probably would do it. But GPS's read out MPH constantly so should not be for long.

Tim
 
A buddy has a 25 Suzuki Mega I would put up against ANY factory 25 motor.

And yes the older 25 OMC with the pin drive were actually stronger than the newer motors with thru prop exhaust. One of my uncles has a one year newer 25 Johnson than the one I had. He has it on a 1652 Sea ark. I run right next to him with my 15 Suzuki EFI I have right now. They both run right at 21 mph.

I am not a fan of Johnsons lower HP motors. They are reliable but are just too slow.

I got rid of my 40 ETEC for this very reason. They are pigs and just do not have any power. I had this on a 1760 Express. 27 mph.
 
[url=https://www.tinboats.net/forum/viewtopic.php?p=342535#p342535 said:
earl60446 » 22 Feb 2014, 23:07[/url]"]

Not sure how moving the gps in the boat throws it way off unless you lose signal. That probably would do it. But GPS's read out MPH constantly so should not be for long.
If you are at your top speed getting a consistent reading, try moving the GPS forward toward the bow. The speed that you move the gps is added to the boat speed...momentarily anyway. If your GPS locks in on the maximum speed attained, that's what it will read.
 
[url=https://www.tinboats.net/forum/viewtopic.php?p=342541#p342541 said:
tomme boy » 23 Feb 2014, 03:12[/url]"]And yes the older 25 OMC with the pin drive were actually stronger than the newer motors with thru prop exhaust.
Please permit me to disagree with the above statement. The "pin drive" 25hp OMC engines were the least powerful. These 22cu.in. powerheads were used from 1957 up to 1976. In 1969 the Factory added different pistons, cylinder head, and carburetor to the 18hp 'Fastwin'. They ran them a thousand RPM faster and rated them at 25hp. It was named 'Sportster'. Like the old 18hp, it only weighed 85lbs. Here's a picture of one I rigged to a 10ft Sears boat. I weigh 200+, the boat GPSd at 34mph with the 2blade brass prop(12P) and the 3/4 riser block. The engine would do 25mph on a MV1648(10P) and 29mph on a 12ft Mirrocraft vhull(11P).

The new powerheads Starting in 1977 were 31.8cu.in.. These formed the basis for all the next 20,25,28,30,35hp engines up to 2005. They weighed 115-125lbs. The thru-hub exhaust started with the top models and eventually all the models. When the smaller 'old style' lower unit was used on these motors, OMC used a splined propshaft. The extra torque of the 31.8 cubes was more than a shear pin could handle. I have seen these engines, tuned right, run as high as 37-40mph on a 14ft aluminum boat.
 

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The ones I am talking about was the early 80's models that were pin drive. All white with a orange stripe and lettering. Might have been the commercial motors. They were the bigger c.i. head.

The newer thru hub models were detuned because of emissions. They are pitiful for a 25.
 

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