johnson A-50

orlandoclippertim

Petty Officer 2nd Class
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Jun 2, 2011
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106
Just got around to bringing down an old motor from the attic. It is a johnson
model a-50 2 cylinder. I had no idea it was from 1930 ! I thought maybe 1945 !
It was stuck when I got it . That was 25 years ago. I got it un-stuck and appart
in a big box. Do yall think I could get away with just hoaning the bores and maybe
changing the rings ???????? Could I re-use the old rings by glass beading the outer
surfaces ????? assuming they aern't broken at the corners from when it stopped.
I am guessing it lost water and stopped. I can't remember if it has a piston pump
or the water induction thing....

I also have a merc. KD-3 1 cylinder thats almost ready to go back together.
Were these used just on canoes ????? the clamp looks too small to fit onto
a modern transom !

Tim
 

1946Zephyr

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Oct 21, 2008
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5,556
Re: johnson A-50

These are cool motors. The first model year that was an alternate firing twin in the A model and the cylinders are under over, vs. opposed. Quite a lot different from the 1929 model. if the cylinders look good, then by all means, hone then out and call it good. As far as rings go, I hope you can re-use them, because finding new ones may be a bit tough. Try Engine Blade and Prop, to see if they have any. Also try Sea-Way Marine.
 

orlandoclippertim

Petty Officer 2nd Class
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Jun 2, 2011
Messages
106
Re: johnson A-50

Yes, thank your zephyr.... The cylingers look fine. The rings look good but I have to carefully examine both
with a strong lite and magnification. The engine looks to be in very good condition. even the plate with the
coils LOOKS good. Havnt looked inside the fuel tank yet. (cap kind of glued on ..... have to figure a way
to get it loole without blowing up the tank or scratching it ! I was thinking it might be a neat
emergency engine for my new 15 foot orlando clipper runabout.
We also have a 1926 evinrude with the brass flywheel and lower.
The other engine I brought down from the attic is a mercury kd-3. Tiny little thing. couldn't be much HP.
Is this a canoe engine ? the transom clamp only opens to what appears about 1+1/4 inches .........
It is almost ready to do final assy. except it needs new rubber inpeller.

I will hoan and clean and see what happen. Looks like a high quality and well made engine !

Tim in Orlando
 

samo_ott

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Jun 18, 2006
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5,125
Re: johnson A-50

Tim, try the Aomci.org website as they deal with the older engines like you have. They can help source parts for you.
 

1946Zephyr

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Oct 21, 2008
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5,556
Re: johnson A-50

Yea, those were great old motors. I didn't think there was much wrong with it. :D

One thing for certain in those old classic, is quality is never outdated.

Be careful with the rings, incase you have to use them. sammo_ott's advice is good too. You should consider joining up in the AOMCIA.
I had a '29 and a '30 and both were great runners and always seemed to be ready to run. I think these were also the pioneers of the later Light Twins of the late 30's and early 40's.
 

Chinewalker

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Aug 19, 2001
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8,902
Re: johnson A-50

I've got an A-65 (a few years newer, but basically same motor) and it's a fantastic running little kicker! Surprisingly quiet, too - as long as I keep the exhaust cutout covered! At one time, it was able to plane off our 12-foot tinny with me in it. It can no longer do that, through no fault of the motor... ;-) I was a foot shorter and 140 lbs. lighter back than....

A light honing and cleaning of all carbon may be all you need to get the compression to a workable range. Be sure to run that RICH on oil mix. I ran mine on a 12:1 mix (quart oil to 3 gallons gas). I think the original recommendation was richer than that...
 

orlandoclippertim

Petty Officer 2nd Class
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Jun 2, 2011
Messages
106
Re: johnson A-50

Chinewalker:
Great news... I got the crankshaft unstuck from the cast tonight. It appears it was just fowled with carbon like the pistons were.
I see the bronze rods are very slightly bent and twisted just a little. Can I massage them back straight and paralell without hurting them ? Nothing seems loose antwhere I can see so far.
Tim
 

Chinewalker

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Aug 19, 2001
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8,902
Re: johnson A-50

As long as they're not too bent, I would think you could get them straight again without weakening them. Not exactly a high performance motor here. You can use plate glass to check them for straightness.
 

orlandoclippertim

Petty Officer 2nd Class
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Jun 2, 2011
Messages
106
Re: johnson A-50

Not sure how they got bent. Theywere bent before I got it. It appeared that the motoe started overheating and the oil in the gas started to burn and carbonise. appairently, from how it was packen between the crank and case, this carbon packed in there gradualy stopped the crank from turning. I am guessing that this drag increased the load on the rods untill it came to a stop. They are bent and twisted justa little and they are just the same. There was a lot of carbon between the pistons and cylinder walls too. I would guess bronze is maleable enough to tollerate a little cold working.
Do yall know if the crank was painted a color or just left bare aluminum ?

Thanks for all the replys !
Tim
 

1946Zephyr

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Oct 21, 2008
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Re: johnson A-50

Wow that's too bad. Fortunnately, you can pull the cylinder jug off and clean the pistons off, but finding new rods will be a bit tough. Hopefully, you'll get lucky and be able to save the ones you have. Like I said before, those old A model Johnsons are great runners and not much is needed to coax them back to life. Johnson motors built a great reputation on the Model A ight twin.
 

orlandoclippertim

Petty Officer 2nd Class
Joined
Jun 2, 2011
Messages
106
Re: johnson A-50

Zephyr:
I was able to straighten the rods pretty easily. Those little things are pretty soft compared to steel or aluminum. I am about ready to put the pods, pistons and crank back together. Just have to cut out some paper gaskets to put on the machined faces.
Hope to have the core back together in a couple of days. I havnt even hardly looked at the lower yet.
My gas tank has some bad dents that look like they were made with an ice pick. Not ones I could blow out with air.
Was considering cutting it open to massage out dents- then reweld when done and work down the beads to blend into surrounding area. do you think that would be too drastic ?

Tim
 
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