10 hp johnson runs rough

[Ratchet]

I have a 1956 10 hp that runs rough just off idle<br />I can troll with it and from about 1/2 throttle to wide open it runs great. I cleaned the carb. did I miss a passage in there somewhere?

 

[Paul Moir]

Re: 10 hp johnson runs rough

Check your link and synch. That is to say, synchronize the spark timing with the throttle plate opening.<br />Also, midrange problems can come from a weak spark. Do both spark plug leads produce a spark that can jump a 3/8" gap?<br />Funny question, but did you replace the spark plug leads? Are they made from automotive spark plug wire?