Mystery 1941 Johnson Seahorse

[CentMassBass]

Have an old Johnson Seahorse serial # is 403832 Model MS 20. From what I have found and dig up it’s a 1941 1.5 hp. It was my grandfather’s outboard. Last ran in 1966 was kept in its box has compression. I would like to try and get it running. How to test for spark on a old outboard like this? I cannot attach photos from my iPhone. Color of motor is silver with red writing. It has 2 cylinders which throws me for a loop because the 1.5 motor should only have 1 cylinder. All help would be appreciated.

[Buccaneer]

I didn’t find a photo of a MS20, but found this video of a 1940 MS15,
which I assume is similar.
You’re correct, the MS20 should be a single cylinder.
If you found MS20 on the rope pulley, I’d say someone put
that pulley on your two cylinder engine.
Can you email the photo to one of us so we can post?

https://youtu.be/raBR6RaGtU8

Prepare to be boarded!

[CentMassBass]

Buccaneer, thanks for follow up. The ms20 is stamped on the cylinder housing along with the serial number. I also came across the YouTube video that you showed as well in my research. I also have a repair parts catalog for ms20 and md20 outboards as well. I wish I could attach or send the photos/ images but size limitations and file types do not allow.

[CentMassBass]

Buccaneer I emailed you some pictures of what I have. The original starter rope was replaced by my grandpa he used a small block of wood and some clothesline rope it works to spin it over.

[Buccaneer]

I sent you a PM.

Prepare to be boarded!

[oldemtr]

Here’s a parts manual for it :
https://www.ebay.com/itm/1941-1942-JOHNSON-1-5HP-MS-20-MD-20-OUTBOARD-MOTOR-PART-MANUAL-43-300779-/361211281683

And an expired E-bay listing :
https://www.ebay.com/itm/Vintage-1941-Johnson-1-5-hp-Outboard-Motor-Model-034-MS-20-034-/184142830849?nma=true&si=pZdilo3dfyqPTx3vZMH1yJ%252FBZoo%253D&orig_cvip=true&nordt=true&rt=nc&_trksid=p2047675.l2557

Good luck

• This reply was modified 4 years ago by oldemtr.

[CentMassBass]

Hey thanks for the reply. I have the repair parts catalog already. I also have seen that ebay listing also.

[opposedtwin]

So does it still have 2 cylinders?

[Buccaneer]

Following are photos of the motor in question.

Prepare to be boarded!

[lloyd]

That is not an MS20. It is an HS20, 2.5 HP. And a very nice looking one. Go to the thread about the TN that wasn’t running right. Much good info there about these similar motors.

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Tuglife

[Author]

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