1972 johnson 25hp runs rough

[joe priddy]

Just purchased this motor. Previous owner tanked it and seemed to run good. Took it out and at about 1/3 throttle rpm's dropped to idle, then catch again and then back off again. What are the possible problems? Thanks

 

[jasper60103]

Re: 1972 johnson 25hp runs rough

Compression and a spark test is a good place to start. Congrats on your new motor. Good luck.

 

[mables]

Re: 1972 johnson 25hp runs rough

Agree with above^^. Does it only do it at 1/3 throttle or does it continue when you go the rest of the way? If no issues are found with compression and spark then the next step is a good ol' carb cleanin.