1956 Johnson 10hp Tiller won't hold speed

[ricklab]

I recently purchased this motor. The tiller will not hold position. When starting I place it at start and it rotates back to slow when I pull start it. Is there a way to adjust it to make it hold? I have the service manual and have not found a way to do this. Thanks

 

[JB]

Re: 1956 Johnson 10hp Tiller won't hold speed

That is a "dead man" throttle, Rick. It is supposed to go to slow when released.

 

[F_R]

Re: 1956 Johnson 10hp Tiller won't hold speed

Rick, there is supposed to be a friction plug in the twist grip to make it stay where you put it. However, it sounds like somebody has been in the magneto and didn't adjust the coils' clearance. They are supposed to be flush with the machined edges on the posts on the aluminum armature plate on which they mount. If they are too far out, they will drag on the flywheel magnets, which will rotate the armature plate toward slow/off. Wears the daylights out of the coils too.

 

[Chinewalker]

Re: 1956 Johnson 10hp Tiller won't hold speed

Hi Rick,
F_R is correct - there is supposed to be a couple parts inside the tiller grip to give it some staying power. There is a fairly heavy spring and a cup that holds it in place. They are often missing, particularly when someone removes the handle and the spring goes flying - been known to happen. Might be able to improvise if it is missing. Spring is about 2-inches long and about 5/8-inch in diameter. Compressed it goes down to about 1-inch...
And checking the coils is a good idea, too. Easy to check on that one - turn the flywheel by hand and watch the armature plate for movement...
- Scott

 

[ricklab]

Re: 1956 Johnson 10hp Tiller won't hold speed

Fixed It! Thanks for all the advice. I had replaced both coils and sure enough one was rubbing against the flywheel. Now it holds the throttle position perfectly.