Johnson '55 5.5hp model CD-12. Low speed adjustment

The engine starts readily and runs at high speed but I can't get it to run at low speed. I have tried to adjust the throttle cam synchro. and thought that would fix it but it really had no noticeable effect. It seems to surge or hesitate as I throttle to high speed.

I have been working for a few weeks to restore this old motor. I started by replacing the impeller and it now pumps water. I have removed and cleaned the carburator and get spark at both plugs. I have replaced the fuel lines (they were cracked), lower unit lube, spark plugs, set the points at .020.

I also notice that the insulation on the coils is cracked. Could that be contributing to the problem? I was hoping not to have to replace them and I am getting good spark at the plugs.

Any help would be appreciated.

Re: Johnson '55 5.5hp model CD-12. Low speed adjustment

This may help until those more familiar chime in..

http://www.outboard-boat-motor-repair.com/Johnson/default.htm

Re: Johnson '55 5.5hp model CD-12. Low speed adjustment

You need new coils. Those ones are toast.

Re: Johnson '55 5.5hp model CD-12. Low speed adjustment

Absolutely!! No other way, you have to replace those coils. It will run like new.

Re: Johnson '55 5.5hp model CD-12. Low speed adjustment

I had the same problems with a '58 5.5hp, took the advice of the guys on the forum and my "restoration" really only required a bit of elbow grease and a tune-up. Replace the coils and make sure the wires are sound. Also the manual mentions that the coils have to be aligned under the flywheel and (don't be like me) once you've gotten everything back together, make sure you do the whole Linc & sync thing or it won't run at low speedand you'll look rather foolish when you figure out what you didn't do Have you done anything with the carburetion yet?

Re: Johnson '55 5.5hp model CD-12. Low speed adjustment

I have a couple of CD-11's I'm working on and the above info is bang on. If the coils are cracked, change em. You also might need to drop a carb kit in it but they are cheap and easy to do. It'll take longer to re & re the carb then it will to rebuild it.

Re: Johnson '55 5.5hp model CD-12. Low speed adjustment

OK new coils then! Thanks to all for the great information and feedback.

pgdignan - I have only removed and cleaned (sprayed with carb cleaner) the carb. I was reading your thread on your '58 troubles. Sounds like I should do the carb kit thing too. I think I recall that you removed the cap at the top of the carb and ran a strand of copper wire through the ports and found some gummed up areas that the carb cleaner didn't reach. I didn't mess with the cap because I couldn't see how to remove it. ???

Thanks again.

Re: Johnson '55 5.5hp model CD-12. Low speed adjustment

Yes, get a carb kit. The OMC ones include a new float as the old cork ones have usually fallen apart by this time. The cap at the top is very important to remove to clean up inside. It usually has to be destroyed to remove it but all the carb kits include a replacement. Dont destroy yours until you are sure you have a new one. To get it out, hammer an awl or small screwdriver through the top and pick/pry it out, but dont go in too deep.

Re: Johnson '55 5.5hp model CD-12. Low speed adjustment

rickdb1boat posted an excellent website that will guide you through all the steps involved in tuning up your 5.5 hp including rebuilding the carb. I suggest you check it out.

http://www.outboard-boat-motor-repair.com/Johnson/default.htm

Re: Johnson '55 5.5hp model CD-12. Low speed adjustment

Thanks rickdb1boat for the link to the website. It's excellent. I have to put the motor away for awhile. Hunting season ya know. I'll pick up with the carb rebuild and coils in a few months. If all goes well, I will venture into a complete external restore-paint decals etc. for the motor and gas tank.

I was going to sell this thing but I'm having too much fun. I don't even own a boat!.... Thanks to all