Johnson, 20R71S, 1971

by Tim
(Western Kentucky)

Johnson, 20R71S

Replaced one of the coils yesterday and put flywheel and pull cord back together. Torqued flywheel to 45 ft. lbs. Engine usually starts with first try, but not this time. Every time I turned the key the engine would jump hard (never has done this) and the throttle control on the tiller arm would advance by itself. Tried to start it several times until a piece broke off. Took off pull cord and flywheel and found that the throttle control cam broke. Upon further inspection I found that the butterfly on the carb is staying open even when I operate the butterfly control by hand.

There is a black lever on the top rear of the engine that I think has something to do with the throttle. It moved quite a bit while I was installing the coil and reinstalling the flywheel and pull cord.

I've attached four pictures, one of the broken cam, one of the location the cam attaches, one of the butterfly on the carb and one of the black lever.

So my question is what could I have done to cause this by just replacing a coil? By the way I never removed the armature plate.

Any help on what went wrong and how to fix the problem would be greatly appreicated. Also, any help in finding a new Throttle Control Cam would be great. I've checked internet and locally with no luck.

Thanks in advance for any and all help.

Tim.