Old Johnson

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labrador guy
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Old Johnson

Postby labrador guy » Thu Apr 20, 2017 10:46 pm

Hi guys, what can you tell me about a KD15 Johnson. I just picked one up and I am lost but I am learning! This motor is complete and needs a bunch of cleaning. Peter Hunn's outboard bible tells me it's a 1941 model. Must be one of the first vertical twins that Johnson built. Maybe a precursor to the QD series? Rewind is now working after much fusing with those wave washers. I have no spark. Getting the flywheel off was a bugger. I found three of those 1/4x 24 threaded bolts! I read about them in another tread. I used the original rewind cog bolts to get a pry on the flywheel and managed to get it off. Strange condensers, strange rotary valve system. Is there a seal in the middle of the cylinders? How does this motor maintain crankshaft pressure? Gonna test the coils tomorrow. Any info or insight on this puppy will be appreciated.


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Re: Old Johnson

Postby kevinrude » Thu Apr 20, 2017 11:02 pm

Well, LG, I have absolutely no insight for you, but I do have two of these motors in the garage, so I will be watching this thread closely. Good luck! I think JoeCB fixed up one of these a few years back, and that guy is a better mechanic than I can ever hope to be. Maybe he'll be able to help you out?

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Re: Old Johnson

Postby Wedgie » Thu Apr 20, 2017 11:16 pm

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Re: Old Johnson

Postby crosbyman » Fri Apr 21, 2017 12:03 am

http://boatinfo.no/lib/johnson/manuals/ ... on.html#/0

the book of knowledge page 97 covers a bit on carburation of KD's ....other sections not to rich with info

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Re: Old Johnson

Postby Mumbles » Fri Apr 21, 2017 12:43 am

I think the honor of being the first alternate firing Johnson would have to go to the 1930 A-50 and K models. They'd been around a few years before your motor was built and yes, your 71 lb. 9.8 horsepower KD-15 motor was the forerunner to the QD series and calls for an 8:1 fuel mix using 40W oil. AeroShell Oil 80 or AeroShell W80 aviation oils are both SAE 40 W oils. Two rings on the large rotary valve seal the crankcase. The original square condensers were rated at .22 uF and the Champion 5MJ plugs are set a .030" and the points at .020". The magneto is kind of unique with a separate coil for each cylinder. You say you pried the flywheel off? It would be better to use a puller to avoid risking any damage to the flywheel.
Johnson KD-15.jpg
Johnson KD-15.jpg (78.09 KiB) Viewed 1430 times
KA 37 Rotary Valve.JPG
KA 37 Rotary Valve.JPG (2.97 MiB) Viewed 1430 times
IMGP1800.JPG (2.91 MiB) Viewed 1430 times
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labrador guy
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Re: Old Johnson

Postby labrador guy » Fri Apr 21, 2017 6:51 am

Yup that is the baby! Mine does not have that kill button. It has two metal tabs that look like they contact the housing when the go lever is moved all the way to the left. What is going on with the exhaust damper? A leaver from the carb controls, opens a metal washer on the underside of the exhaust duct. Maybe exhaust relief? Your motor has a cutout on the muffler. Mine has a bolted on cover. Were these motors racers? Plenty thick oil ratio, maybe trying to seal the crankcase? This motor is a learning experience for me. I made an offer and it followed me home!
thanks dale

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Re: Old Johnson

Postby labrador guy » Fri Apr 21, 2017 6:54 am

Try this!
IMG_1631.JPG (2.96 MiB) Viewed 1401 times
IMG_1626.JPG (2.26 MiB) Viewed 1401 times

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Garry in Tampa
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Re: Old Johnson

Postby Garry in Tampa » Fri Apr 21, 2017 10:25 am

The racing model had roller bearings on the crankshaft and top, bottom seals, side draft carburetor and a slimmer gearcase with a higher gear ratio. Also an open exhaust and higher compression ratio with two ring pistons. . . :D
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Re: Old Johnson

Postby ddwilson » Fri Apr 21, 2017 1:03 pm

I have both A-50 and K-50 motors the original rectangular condensers you are not going to find. Mid 60s chevy condensers work just have to drill and tap a hole to mount them where the originals were. I made little covers to go over the bottom of the mag plate to cover the modern ones I put in there. They work fine neither motor has given me any issues since I put them in.
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1930 Johnson A50
1932 Johnson K50
1951 Wizard WG7
1953 Wizard WH7
1958 Johnson QD19
1959 Johnson CD16
and the list goes on........

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Re: Old Johnson

Postby mercuryman » Fri Apr 21, 2017 3:07 pm

I have a KA38 I recently acquired and can't get the flywheel loose. I have pulled the puller as tight as I dare, applied heat and penetrating oil and tap on puller bolt, won't budge. If I pull real hard what will break first, bolt or flywheel ? I have cleaned the points through the little window on flywheel and got the motor running good maybe I should let it alone.
Mercury -MK25, MK10, KH7, KG7,KG4, KE4,KE4, KF5,KF3,KE3
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Johnson - QD15, HD26, TD20, KA38
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Evinrude- Foldlite 1930, ELTO - LW #309, 1951- 7.5, Zephyr, 68 3 hp
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