Johnson KA37 starting and running questions

[DAN UMBARGER]

Got my Ka37 back together and ran it briefly on my stand then tried to run it in a barrel to get back pressure and a load on the prop. After finding one the Champion plugs started fouling I put in a pair of new NGK AB-6 plugs and it ran decently only with the little exhaust cutout cap removed. Would not start in the water with the cap bolted on. The high speed is set at about 3/4  and the low speed is about 1/4. Haven’t had the motor apart yet so I don’t know what the internal exhaust area looks like. What would be the most logical reason it won’t run with the cap on? When I got the motor the cap was missing so I ordered one from the Penns now I think I know why it was missing. I’ve never run one of these motors so I don’t know what the initial settings should be…any thoughts? Also as Buc has said earlier it prolly won’t pump water in a barrel…needs to be on a boat but when I do get it on a boat where will the water exit the motor .. don’t see any drilled holes or any kind of water discharge. After I get the motor running well then I’ll start cleaning the motor up and tackle the bashed in tank corner…man I’m not looking forward to that!!!! Looks to me like the tank was polished along with the lower unit being polished and the rest painted….am I correct in that thinking? Are there any good pics of a nice K model Johnson out there?

[stanley]

There is no “tell tale” for water flow,you’ll just have to trust and verify by touching cylinders.Here are some carb set up directions.You need to run 8:1 mix to insure sealing of internal rotary valve.

• This reply was modified 1 year, 7 months ago by stanley.

[Mumbles]

To keep the motor cool while testing it, there is a plug at the bottom of the cylinders which can be removed and replaced with a fitting so you can hook it up to a garden hose.  They will over heat trying to run it in a barrel as they need the motion of the boat and the thrust of the prop turning at full RPM for a few seconds to prime the motors  pressure/vacumm cooling system. Once it’s primed, speed can be reduced.

With no conventional water pump or impeller, water is forced into the motors intake at the rear of the prop by the prop and exits in front of the prop being pulled out of the motor by the low pressure  area in front of the prop. Simple design but it works.

KA models are notorious for having the exhaust pipe coming from the cylinders plugging up with carbon from years of using 30W motor oil at the 8:1 ratio.  This might be why the cutout was removed, so the motor could breath. With the tank off for repairs, it’s easy to remove the exhaust cover and clean it out.

 

First photo shows the motor with exhaust cover removed and a 90° pipe fitting installed below the cylinders for a garden hose.

Some Bondo work and paint for the tank.

 

• This reply was modified 1 year, 7 months ago by Mumbles.
• This reply was modified 1 year, 7 months ago by Mumbles.

[HARRY D. NICHOLSON]

The worst carbon build-up restriction area is just under the powerhead inside the tower.

• This reply was modified 1 year, 7 months ago by HARRY D. NICHOLSON.

[squierka39]

I had a KA-10 with the same problem, it would only run with the cover off on the muffler. Pull the powerhead off and you’ll see the restricted exhaust openings in the leg. They are often clogged. Here’s one after I cleaned it up. You can see it goes around a corner, this is where it gets gunked up, and also in the muffler itself.

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