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Repair 4 hp two stroke ?

5K views 21 replies 10 participants last post by  dabnis 
#1 ·
A gift came to me a two stroke 4 HP Johnson Outboard.
It needs repair. I have somewhat of an issue with the way a two stroke spews oil fumes and is not very kind to the environment.
It seems not to have much of spark for what I can see. I put a test light in line before the coils and it lights up pretty good. I found a plug with three female but only two male pins before the coils and tested at that location. Female side marked A,B,C, all light up. It makes sense that only two male pins are used because this engine has just two plugs and two coils. The plugs seem to have weak yellow fire jumping the gap not a bright blue. Some times I do not see a spark.
Would both coils or both plugs fail at the same time ?
Coils seem to cost $20 - $35 for a 2 Stroke
It would be a used engine after spending say $70
A new 4 Stroke outboard Cost $1300
Try to repair or buy new ?
Kind regards, Lou
 
#2 ·
Lou

I don't understand the quandry....repair for $70 and use it, or spend 1300 on a new one with no idle adjustment, prone to ethanol issues, no factory support, etc, etc. For me, I would repair the old one, bank the savings or pay down my mortgage.

Just read here on issues folks are having with brand new out of the box engines.

You are in the wrong hobby/lifestyle if you have issues with exhaust. Sailing for the most part requires some sort of ICE to get you to and from the sailing, and to help you out of danger when the wind dies completely, unless your boat is small enough and close enough to the water to row.

The decision is yours but $1200 saved by using the old engine could be donated to the carbon cause of your choice, put in the bank or buy food for those less fortunate than you.

No brainer in my book, but YMMV

best of luck
 
#3 ·
Concur - sure a 2 stroke is not as clean, and some folks are willing to pay for salve to their conscience.

On the other hand a 2 stroke will last forever, burn the ethanol and the water and is lighter, faster to torque up - and most important - start reliably.
 
#4 ·
I love my little Mercury/Tohatsu 5 hp two stroke. So light my wife can handle it (well, with a little help), and so easy to work on that I've torn down the whole carb in the cockpit in a rocking anchorage.


That being said, I absolutely *HATE* having to mix fuel/oil every time i fill up. Makes me...and it is a bit noisy.
 
#5 ·
My two-stroke Evinrude 9.9, aka "the lawnmower", is the same age as my regular crew, who incidentally has loaned me his basement for repairs a couple of years ago. We keep it going, it gets us in and out of the marina, and if the wind is light we just sail slower. C27s mount their motors in a hole in the transom, and four-strokes just don't fit in it.
 
#6 ·
You didn't say what year? I think they went to electronic ignition about the early 70's. If yours is electronic you should see a bright blue/white spark at the plug. Maybe try a new plug? If not, the exciter or trigger coil may be bad. A shop may be able to test it and the ignition coils. I have had many 2 stroke outboards and motorcycles. Properly maintained, new plugs once in a while, the are bullet proof and will last basically forever. The smoke is less annoying than someone smoking cigarettes, to me anyway.

Paul T
 
#7 ·
Year is a big ?? It is a model # 4R77B and the serial # is E4626661 I think it is made in the USA. Johnson sea horse 4 HP. It is always in gear no N or reverse and it is a short shaft. The plugs on it's sticker call for a Champion L77J4 The plugs in it are NGK The coil packs Have a orange wire coming to them and a plug wire coming out. The plug wire seems like it is made in the coil. I am not sure how to test the plug wire to see if it is not working ?
Would both coils go bad at the same time ?
I have found a lot of coils on the web pages. I need to find the right ones or give in and try find a repair shop.
Any reply helps I think I can fix it. Wires and lights are not my strong suit but I am persistent. I can start changing parts and plugs and wires a few good folks posting will help me to change the right ones first.
The pull starter was a mess and that was and easy fix. Just need some spark Thanks, Lou
 
#8 ·
It is a regular shaft 1977. It is hard to diagnose electrics from a distance, but for starters, no the coils don't both go bad at once. I have several Johnson 2 strokes and did have one of your same model for a few years. If I come up with some sort of brilliant idea for yours, I will get back to you. I will consult with my outboard expert (my son).
 
#9 ·
I can take some pictures with my phone. I am not very good get a picture from the phone to post here on sailnet . The coils have an orange wires coming into them going back up the orange wires they go to a plug with two male ends that comes from three female plugs marked a,b,c the two orange wires can only plug in the correct way. All female ends on this plug light up the test light. From that point ( the three female upstream two male pins down stream plug ) the next down stream place to test seems to be the spark plugs. I do not see a way to disconnect the orange wires when the enter the coil or a way to disconnect the plug wires at the coil. Thanks, Lou
 
#12 ·
The 4R77B makes it a 1977 ? The compression was 60 lbs The exciter coil must be good. It is what lights up the test light at the connection plug. I am not sure about a ground kill it must work from a point at the throttle. Thanks again, Lou
 
#13 ·
60lbs? Not sure what the spec is? but it sounds a little low? Maybe squirt a little light oil in the plug hole and try it again? I think you said you were getting a weak spark from each plug? If all the wiring reads good with an ohm meter you may have bad ignition coils, but that may be a stretch?

Let us know what you find.

Paul T
 
#14 ·
Easy come easy go. They want it back. I have it running in a 55 gal drum sounds good one pull to start it.
I pulled the coils out and checked the coils with a ohm meter. I found some info on this Iboat forum that gave values for the primary 1-2 ohms and secondary 6-8 ohms This engine showed 12 ohms on the secondary? As I said me and wires do not mix. I have know idea what I am doing.
I checked the spark when I put the coils back and it was a little bit better but not a bright blue but a strong yellow and shooting of the plug sides. I cleaned the plugs up this helped the "fire" still not blue.
I checked the compression once more both holes plugs out 60 lbs One of you said to do this It seemed to help the sound.
I noticed the mix Lean rich dials not balanced so I set them to the middle.
Pulled the rope a few times and the pay off came on pull 5-7
Now it will start in one if it is warm.
Lake test Sat I think
The motor has been recalled so it seems. Not a loss to me as it came to me for free. I now have a little bit of an idea what is going on and how to work on one. That's a plus
I wish to thank all of you that gave me an ear and some help Kind Regards, Lou
 
#16 ·
For future reference: Did you check for rust on the magnets on the inside of the flywheel? If they have a coating of rust on them it will impair the spark. Sitting around for a while can cause this. A cleaning with some emery cloth can perform wonders on these little 2 strokes.

Down
 
#17 ·
I did not remove the fly wheel as I felt like the spark from the under the fly wheel was good. I had unplugged some wires going to the coil packs that came from under the fly wheel. At that point I used a test light and it would flash bright and full with each pull. Even a slow gentle pull.
I think the removing the coils and putting them back on and cleaning the plugs that did not seem fouled made it better. The coils might not have been getting a good ground ? They are still over the Ohm range of 6-8 ohms that I found on the other boating forum. These coils both showed 12 ohms. A real electrician, not me checked 12 ohms. I can use an ohm meter like a novice. Understanding values not really.. 12 is half again 8 and 8 is 3/4 of 12 Seems like 12 ohms is way to high ? I put the coils back on and the spark was better.
Oil down the plug holes did nothing for the spark but it is a fine line that makes an engine go. Once she hit she got much better. She was a sleepy puppy. Now she is ready to play.
I have had some 2 stroke dirt bikes and 4 stroke I have no battle as to what is the best they both have a + and a -
Electronics are a mystery to me. I tip my hat to the ones that have skill. They get a good laugh at me but always help me to find the trouble. I try and I just stay at it long enough that I find the fault by will power.
It was my first outboard engine fix. I grew up on lake Erie and the inboard or inboard/ outboard is more my limited fixer upper
I wish I did not have to give it back but like I said learning about it was great reward.
Regards, Lou
 
#19 ·
I was pretty sure that I was making a mistake when I bought a 20 year old 2-stroke Nissan 9.9 with almost no hours on it. I really wanted a new 4-stroke.
I was wrong. I am one of few around here who's engine always starts on the first pull. I am one of few who can both plane the dinghy with 3 people in it and be able to carry the outboard around by myself.
My only mistake was doubting my decision.
 
#20 ·
I recently bought a new 6HP 4 stroke Tohatsu for my fishing boat. The reason I bought a 4 stroke is that carburettor equipped 2 strokes are not allowed on Lake Tahoe. Some time back a bill was introduced to ban 2 strokes on any body of water that eventually ended up in a water supply. The bill was defeated, but not by much, IIRC. I wouldn't be a bit surprised to see that bill re-introduced again.

I have had many 2 strokes and would have bought a new one except for the above.

Paul T
 
#21 ·
You know the water in the 55 gal drum was not something anyone would like to have a drink after even just a few moments of the little engine running.
I have found out this information outboard 2 stroke engines use the 50-1 mix to cut down on some of the waste oil and pollution that comes with a 2 stroke in the water. It is not to do with keeping the plugs clean as the jet size has more to do with this than the fuel mix. Engines run the best when the right mix is used. Changing the mix is not the way to go change the jets to get a rich or lean mix

I am not sure why folks think one engine type is more reliable than the next ? Build quality from the manufacture has more to do with reliability. In engines look at aircraft as the gold standard. Turbine, 4 stroke, last is the 2 stroke. The 2 stokes best points... simplistic and light weight. Very good power to weight ratio. Low build cost for the manufacture = good profit.
Look forward to hear the replies that will come. Kind Regards, Lou
 
#22 ·
You know the water in the 55 gal drum was not something anyone would like to have a drink after even just a few moments of the little engine running.
I have found out this information outboard 2 stroke engines use the 50-1 mix to cut down on some of the waste oil and pollution that comes with a 2 stroke in the water. It is not to do with keeping the plugs clean as the jet size has more to do with this than the fuel mix. Engines run the best when the right mix is used. Changing the mix is not the way to go change the jets to get a rich or lean mix

I am not sure why folks think one engine type is more reliable than the next ? Build quality from the manufacture has more to do with reliability. In engines look at aircraft as the gold standard. Turbine, 4 stroke, last is the 2 stroke. The 2 stokes best points... simplistic and light weight. Very good power to weight ratio. Low build cost for the manufacture = good profit.
Look forward to hear the replies that will come. Kind Regards, Lou
Lou,

Oil/gas mix is important for lubrication, most of the 2 strokes I have had specified 50:1. Some bigger outboards had/have? oil injection, no need to mix.

Gas/air mixture determines power output. Lean, more air, runs really strong until heat builds up and it seizes, don't ask me how I know:D

Years ago there were high speed mixture controls. Best setting was rich until it ran a Little rough then lean it out just enough to get rid of the roughness, no more. Too lean, too hot, seize.

Present day motors have fixed high speed jets which must be changed to adjust the mixture. Slow/idle mixture, Generally about 1-1/2 turns out or until it stumbles on the rich side, then back just enough to smooth it out. I keep mine, both 2 & 4 stroke, on the rich side to avoid "stalling"

2 strokes are lighter for the same HP rating, simple, and in my opinion will last as long, maybe longer than a comparable 4 stroke. different strokes for different folks.

Paul T
 
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