25hp Johnson - the good and the bad?

[pierretheron]

I'm looking into buying an older 25hp motor, probably around the mid to late 80's early 90's. I don't know anything about these models and would like to know if there were any bad batches or years to avoid. I beleive that the 18-20-25 were the same chasis so the 25 would give me the best power to weight ratio, is this true?

I'm also not sure if i what year the 25hp became 3 cylinders or if it was only ever 2 cylinders. Any shared knowledge and opinions would be more than i know.

Thanks

 

[WillyBWright]

Re: 25hp Johnson - the good and the bad?

Good motors. Thru-prop exhaust models would be my preference. Always twins. 35s were twins or triples.

 

[tashasdaddy]

Re: 25hp Johnson - the good and the bad?

you are speaking of engines that are just broken in. check compression, spark, test run. look for marked up bolts that show they have been removed, and find out why. when was the last time the impeller was changed. has it ever been decarbed.

 

[dwagner47]

Re: 25hp Johnson - the good and the bad?

18-20-25 hp prior to 1977 are based on 22 ci powerhead. 25-35 hp after 1976 are based on 32 ci powerhead which made the motor heavier than the 86 lbs that the 18-20-25 hps are. I had a 35 hp mid 1980s that was smaller and outperformed the older 40 hp motors but was a little noisier. I guess someone else liked it too when they used a bolt cutter to cut the steering and control cables and lock and took it off the boat one night. This summer i bought a 1973 18 hp evinrude and I fixed it up. It is fairly light (86 ibs) and performs quite well.

 

[dwagner47]

Re: 25hp Johnson - the good and the bad?

I don't think there was ever a 3 cylinder OMC 24 hp motor.

 

[dwagner47]

Re: 25hp Johnson - the good and the bad?

Correction on my typo - I don't think there ever was a 3 cyl OMC 25 hp motor.

My manual for my 1973 18 hp evinrude says that the 18 & 20 hp motors based on the 22 ci powerhead are rated at 4500 rpm and the 25 hp based on the same powerhead is rated at 5500 rpm. The 25 hp has a different carb jet. One of these 25 hp motors would have a great hp to weight ratio but sounds like they were squeezing the max hp out of the design so used motors may be more tired.

I recently saw a used Yamaha 40 hp 2 stroke that is 3 cyls, very quiet and smooth.

 

[steelespike]

Re: 25hp Johnson - the good and the bad?

I descovered there are a number of builders making 3 cyl. 25s including Force in about 97/98.

 

[pierretheron]

Re: 25hp Johnson - the good and the bad?

Figures and facts, great stuff!!

I presently have a 15hp '89 Johnson that is being run in, it's a superb engine, but i would like a little more power(don't we all), without huge weight gain. I have to carry the motor to the launch and back, no trailer access.

So from what i gather here, i'm looking for a 25hp based on the 22 ci powerhead. Did they ever come out with CDi, or were they all points? I would like to stick to the Johnson brand, i have the Clymer manual so i can service and repair it.

 

[Chinewalker]

Re: 25hp Johnson - the good and the bad?

I am pretty sure the very last year of the 22 cubers had CDI. I rebuilt a 1977 Johnson 20hp (Canadian model) a couple years ago that was CDI and it was based on the older 22 cube powerhead. I would imagine there was a US equivalent at 25.

The 22-cube 25s had several significant differences, more than just a carb or jet change. Different pistons and cylinder head, as well as porting to achieve the extra ponies. The only differences I've ever seen between the 20 and 18 were a slight opening of the reed stops...
- Scott

 

[dwagner47]

Re: 25hp Johnson - the good and the bad?

Thanks Commander - I wondered what the differences were between my Evinrude 18 hp and 20 hp of the same vintage.

PierreTheron:
I have the same requirements that led me to the older 18-20-25 hp. I wanted more hp than 15 hp @ 75 lbs but I didn't want much more weight. Older 18-20-25 hp OMCs are 86 lbs. Anything newer in the same hp range is around 100 lbs. The 18-20-25 hp OMC motors are so easy to work on that I wouldn't worry about having to replace points once in a while. My 1973 18 hp only has the driver coil and points under the flywheel, high voltage coils are mounted on the cylinder head. Newer models may have better sound suppression on carb intake. These older 18-20-25 hp motors are not the quietest.

 

[steelespike]

Re: 25hp Johnson - the good and the bad?

My info states Models prior to 77 are 22 cubes,models after 76 are 31.8 cubes.(oddly stated)CDI begins in 77.
Did a quick check 76 25 hp is 87 lbs.77 25 hp is 102lbs.
About 15 lbs.I'm betting it has more low end guts and it is CDI.I don't know if I would want to lug around 102 lbs.
though.
Pierretheron you may want to optimize your set up.raise the motor vertically until just before blowout (ventilation)becomes a problem.Use 1/4 inch sticks to raise it a little at a time.just be sure the clamps have a good grip.
This could give you 1 or 2 mph depending on where you are right now.
Check the trim(in/out)if one notch seem not enough but the next seems too much you can buy or make wedges so you can gain or lose 1/2 a notch.
A bare bones boat with some size, a big 14 for instance will get up on the water easier than a smaller boat.
When I went from a 15 to an 18 with the same 25 hp. the load performance improvement was amazing.
Don't go by length alone.I have a friend with a 14 that you would bet was a 12 when you see it sitting on a trailer.

 

[dwagner47]

Re: 25hp Johnson - the good and the bad?

I bet the 25 hp based on the 32 ci powerhead has alot more low-end guts than the older one. The older 35 hp I had (same 32 ci powerhead) was on a 13 Boston Whaler which isn't a super light boat. The 35 hp would pop it on plane instantly. It would pull up a skier fairly quickly also. I would not want to carry a 100 lb motor more than once in the Spring and once in the Fall though.

 

[Scaaty]

Re: 25hp Johnson - the good and the bad?

I have to carry the motor to the launch and back, no trailer access.

Well, I have a 79 15hp (yep, terrific motor), and its carrried anywhere IF I need too (kicker on my big barge). Have a middle 80's 20 Johnny (same as 25hp) on a 14 footer, and its a back breaker just tossing it on the transsom once. One heavy SOB.

 

[pierretheron]

Re: 25hp Johnson - the good and the bad?

Any idea what year the 22 ci powerhead for the 18-20-25 was put into production? I need to know what years to rule out in my search. Were these all through exhausts?

Thanks for all the good input, anyone else had a '76 22ci block with CDi? I have a '78 6hp with CDi in excellent shape, never have to touch the electronics...

 

[Chinewalker]

Re: 25hp Johnson - the good and the bad?

Hi Pierre,
The 22-cubers were introduced in 1957. They were kept in the line until 1976 - a run of 20 years! They did evolve a bit over the years, but the same basic configuration. They all had the exhaust exiting above the prop from the bottom of the AV plate - no through-hub 22-cubers. The one 22-cuber with CDI I had was a Canadian motor - may have been different from American versions...
- Scott

 

[BF]

Re: 25hp Johnson - the good and the bad?

I have both an '82 15 hp evinrude, and also a '70 25 hp 'rude... both see action on the same 16' aluminum fishing boat. (tiller type with 4 cross seats, no carpeting or live well).

Mostly ditto on what's been said above.

With an empty boat or a very light load, there is surprisingly little difference in top end speed. But, if you get a "normal" load of a couple people, some gear and a smelly yellow lab, the top end speed with the 15 hp drops quite a bit. It makes less difference when I have the 25 on the back.

The 25 (at least mine anyway) is not even in the same league when it comes to idling/trolling. It's a sputtering / stalling annoyance compared to the 15. It (the 15) idles down smooth as silk and will tick over like a sewing machine for hours on end.

So, when I'm going fishing (trolling) I either use the 15, or more often, stick my 6 hp beside the 25 and just use the bigger motor to run from spot to spot. I have even had both the 15 and 25 hp at the same time (15 for trolling).

FYI, I find my 25 hp to be enough of a PITA to move around, that I usually leave it locked on the boat for weeks at a time. But, I the 15 is handy enough to take off and lock in the boathouse. It feels like the weight difference is bigger than it actually is IMHO. (the 25 feels more piggish than I'd expect)

I also find the 25 is louder and lots more thirsty than the 15....

I don't think that the 25's are bad motors, but I think the 15's are particularly good & smooth. One of OMC's best I think.... Depending on what you want the 25 to do, it might be the hot ticket (pushing moderate to heavy loads) or it might be disappointing (light loads and lots of trolling).

that's my $.02.

 

[iwombat]

Re: 25hp Johnson - the good and the bad?

Something worth mentioning here (in case it hasn't already), is that some of the motors in the late 80's were labeled as 100:1 mix, which OMC later recanted on and suggested 50:1 instead. If someone ran them hard at 100:1 it would probably shorten the life some.

I don't have any personal experience with those, so someone else may want to add some details.

 

[Paul Moir]

Re: 25hp Johnson - the good and the bad?

There were 25hp triples made in the mid 90s in the Belgian plant. I don't think they every found their way to North America though. They were based on the 35hp triple. Different heads, pistons, carbs though. If you're interested, have a look at the B(elgian) models in around '96.

 

[dwagner47]

Re: 25hp Johnson - the good and the bad?

BF - interesting comparison between the newer 15 and older 25 - something I always have wondered about. I bought my 73 18 hp evinrude used and I've been tinkering for a few months to get it smooth running. I'm almost there but at idle it seems to run cold and foul the lower plug and start sputtering. Other feedback on this forum suggests that many others have had issues getting the 22 ci motors to idle smoothly.

Anyone ever add sound proofing to the cowling of an outboard to make it quieter? I've seen kits and I've used them with excellent results on the Mercruiser engine in my bigger boat. I'm trying to decide if it would make a difference for an outboard.

Anyone know what the 25 hp triple made at the Belgian plant looked like? Does BRP have schematics for them on their website?

 

[dwagner47]

Re: 25hp Johnson - the good and the bad?

BF - I've gone for many small boat rides with a smelly yellow lab myself.