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1987 25hp Johnson

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1987 25hp Johnson

Postby Jdunn94 » Sun Feb 02, 2020 9:00 pm

Ok so I have got it running now toon it out Friday after work idles great reeves great in neutral but half throttle to full throttle the boat ibwuld say only goes about 5mph so I have replaced plugs on it so far no different results and also the needle on top of carb the lean or rich neddle is backed out pretty good that’s only way it would start but I did put in the little white plastic bearing pice that came with the rebuild kit for it in the needle with the red pice also so idk if that’s my problem or what but any help would be very well appreciated
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Re: 1987 25hp Johnson

Postby Tenntrapper » Sun Feb 09, 2020 6:24 pm

You replaced the bearing and the "red piece". Are you certain that you got the old ones out? That bearing can be difficult to remove. Is the timing advancing as the throttle opens? Have you got fire at both plugs? The mixture screw(needle) should only be about 1.5 turns out (I think, not sure. Maybe 2.5) other than that, not sure. You said only 5mph wide open. Is it reving up?
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Re: 1987 25hp Johnson

Postby MickThompson » Sun Feb 09, 2020 7:17 pm

I came across this on another forum. I’ve heard that some folks have trouble with their old Johnsons but I can’t say that I’ve experienced that. Wish I could take credit for this literary masterpiece...

End of season maintenance...
With the end of the 2019/2020 hunting seasons coming to an end many will be fogging the old outboard with dreams of spring and fishing season. I was cleaning up an old hard drive the other day and came across a folder titled "outboard manuals". Around 2004 a storm capsized my boat tied to my dock and I was asking on a couple of websites for information about getting a boat motor to run after I got it out of the water. I remember a gentleman sending this to me. I'll just leave this here. Those that don't need or appreciate the finer aspects of maintenance will surely stop reading and go on the next post.

Proper Care and Maintenance of Your Johnson:

I was recently in a doctor?s office doing what we all do there; waiting; and perusing through their ancient magazines, when I stumbled across an article in a sporting magazine, written by a man who was having trouble with his Johnson. His old Johnson was showing signs of aging; sputtering, losing its zip, and finally just totally petering out on him. He became despondent that he couldn?t find a Johnson dealer to work on his Johnson, so he just dragged it back to his garage. He later hitched up his boat to his truck and set out to a nearby town, in search of a shop that specialized in rejuvenating old, tired Johnsons. He soon found one and met several other sportsmen there who were also having trouble with their Johnsons. They discussed the usually worry-free performance of their Johnsons and their usual reliability when the going gets tough. But alas, there they were, in a place of business, comparing notes and discussing their mutual pride over their respective Johnsons and their current dismay over the lack of performance of their Johnsons.
This inspired me to do a bit a research, and share with my fellow water-sportsmen, the proper care and maintenance of your Johnson. Now, Johnsons have been around it seems, since the beginning of time. I remember as a child, watching my dad work on his Johnson in the garage. As an aeronautical engineer, he was constantly tinkering with his Johnson, usually in the garage, because the neighbors didn?t like it when he messed with his Johnson in the driveway. I remember my mom showed absolutely no interest in his Johnson at all, and constantly complained about him always tinkering with it for hours. Once she said she would gladly pay for a NEW Johnson, so he wouldn?t have to give his, such constant attention. He refused, of course. He was just that kind of guy. I learned a lot about Johnson?s from my dad and thought I might share my knowledge about Johnsons with my own buds. So here it is; Proper Care and Maintenance of Your Johnson.

Now, you don?t have to be a mechanic to keep your Johnson smoothly operational. And, it doesn?t depend on the size of your Johnson either. A properly maintained smaller Johnson can be as reliable in a tight spot as a bigger Johnson. Believe me! I know! And often, bigger Johnsons require more attention! They are faster, but in certain situations, speed isn?t everything. But regardless of the size of your Johnson, you don?t want a broken Johnson leaving you bobbing around like a cork in the middle of nowhere! Often, men are prone to just thumping something with a hammer when it doesn?t work right. Don?t try that with your Johnson! All Johnsons everywhere require a spark to get them cranked up, so make sure you have a good spark. A spitting and sputtering Johnson may indicate that the spark is lacking.

Secondly, you should always wash down your Johnson after use, especially if you use it in saltwater. Nowadays, you can get a ?Saltwater Series? Johnson, made especially for these conditions. Salt can build up both on and in your Johnson, which is why both washing and flushing it after use, is so important. Washing the outside of your Johnson is a simple affair and doesn?t require explanation beyond a good scrubbing with a stiff brush and lots of soap, but never organic solvents! However, properly flushing your Johnson needs a bit of embellishment. First, your Johnson is designed with an intake, where water flushes through, and keeps your Johnson cooled off while it?s cranked up. Now there is a special opening on your Johnson that is commonly called the ?pee hole?, where the cooling water runs out. When you return from a trip, right there in your driveway, you should hook up your Johnson to your garden hose and turn in on. This forces fresh water through your Johnson to clean out the salt. You need to make sure your Johnson is cranked at this point, to increase the flow. Now while your Johnson is cranked, swipe your finger through the ?pee? stream. The water should be warm, but not hot. If it is hot, shut down your Johnson immediately, before you cause damage. A hot pee stream indicates that your ?pee? hole may be clogged, or you have gotten sand in your Johnson. This can happen if you use your Johnson in really shallow water. You can try to unclog your ?pee? hole yourself, by inserting a stiff piece of wire or straightened out paper clip, working it back and forth, to ream it out or unclog it. This usually works.

If your Johnson is going to go an extended time without use, you want to burn out the fuel from your Johnson, and just let it run until it quits. This will keep the inner workings of your Johnson from building up layers of crud.
A properly cared for and maintained Johnson should give decades of good service, even to the point of possibly passing it down to your son. But occasionally, as with all things, we may have trouble with our Johnsons. Here are a few troubleshooting tips if your Johnson is acting up on you. If you have trouble cranking your Johnson, that is customary. Johnsons are known for having trouble with cold starts. If you can keep your Johnson in a warm place overnight before you know you are going to require a cold start, this would be beneficial, but is only feasible with smaller Johnsons, as larger ones won?t fit through your front door. Trouble cranking your Johnson may also be caused by shorts. While some Johnsons have been known to work even with shorts, you always want to try to operate your Johnson without any shorts at all. If you don?t have any experience dealing with shorts or removing or eliminating shorts, you may want to contact an expert.

If your Johnson is running hot, you may have a defective circulation, which I?ve discussed, or your Johnson just may not be properly lubricated, which other that using the proper weight and amount of oil, goes beyond the scope of this discussion.

If your Johnson simply loses power at an inopportune time, this could be critical, and even dangerous! This could be caused by a loss of compression in your Johnson, which may mean that simply, your Johnson is just used up!

If your Johnson vibrates, that could mean several things. First, it could mean that it is not firing on all cylinders. Second, it could mean that your Johnson is simply loose, and requires tightening down. Thirdly and more seriously, it could be caused by failure of the bearing or loss of lubrication on your crank shaft.

If you can?t turn over your Johnson at all, it could be any number of things including rust, crank shaft damage, poor all around lubrication of your Johnson, or even damage from a previous overheating. If your Johnson backfires, take it to a certified Johnson Mechanic right away! Repeated backfiring could cause permanent damage to your Johnson, and who wants that!?



These are just a few things that could go wrong with your Johnson, and what might be causing the problem. I will end this discussion with fuel selection and additives. Fueling your Johnson is a critical factor in maintaining peak performance. Many different Johnsons require different octanes for optimal performance. Check your Johnson Operation Manual. However, there have been some recently developed additives that can increase the performance level of your Johnson. Most of the additives are Ethyl-based, and one of the most important factors for performance was found to be the purity of the Ethyl chosen for the work. Some authorities claim that very impure Ethyl alone could be counted on for success, while others said that a hitherto unreacted Ethyl was best, while still others claim both of these should be avoided because they produce the byproduct, Ethyl hesitate, which cannot be overcome, and can cause build up, and internal damage in your Johnson. Other additives that have been recommended are Ethyl stimulate, Ethyl vibrate, and Ethyl reciprocate, but Ethyl palpitate was found to work best to keep your Johnson running optimally, while Ethyl refrigerate should be avoided at all cost.
In closing, all these suggestions are not necessarily restricted to Johnsons, but can be used with any recreational power system as well, it?s just that the name, ?Johnson? is so widely recognized in the sporting community?. So, gentlemen, good luck with your Johnson (or whatever you call it!)
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Re: 1987 25hp Johnson

Postby RUGER » Mon Feb 10, 2020 5:53 am

:rotf: :rotf:
Pffft forget that, I'm going fishing.
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Re: 1987 25hp Johnson

Postby Jdunn94 » Mon Feb 10, 2020 7:27 am

Thank is for the information and yes I have replaced both pices I’m going to check to see if I I didn’t get the other bearing out
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Re: 1987 25hp Johnson

Postby Tenntrapper » Mon Feb 10, 2020 8:40 am

I thought of a couple other things to try. I went through the same issues with a '72 Johnson 20hp. If you rebuilt the carb, did you adjust the float level? Also, when I rebuilt the carb on mine, the kit came with a plastic float pivot pin. After one tank of ethanol gas, it didn't run for crap. The ethanol caused the plastic pin to swell and stopped the float from moving. I made a new pin from a piece of metal coat hanger. Has worked great since. As I said, mine was doing the same thing, but I just can't remember exactly what it was. I'll keep thinking.
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Re: 1987 25hp Johnson

Postby Tenntrapper » Mon Feb 10, 2020 8:55 am

I think I just remembered. In the bottom of the float bowl, there is a high speed jet. I think mine was funked up underneath it. Put a couple drops of Kroil in there and let it sit. I had to grind the sides off of a flat screwdriver to fit it in, and not damage the threads. Take out the jet, and clean out that passage. Be very careful to not damage the threads. The price of that float bowl is outrageous. Part number 19 is the high speed jet.
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Tenntrapper
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Re: 1987 25hp Johnson

Postby Jdunn94 » Mon Feb 10, 2020 2:59 pm

Ok I will try both thank you for more advice soon as this rain stops ima tinker with it again
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