78-79 55hp Evinrude acceleration issue

[talbee]

My friend has this motor that bogs when getting up to speed with the motor cover on, but accels faster when it's off. Thoughts?

 

[hardwater fisherman]

Maybe an exhaust leak? Or maybe plug wires arcing on the cover latch?

 

[talbee]

any other thoughts?

 

[ondarvr]

any other thoughts?

If the symptoms are as you described, then those are the two things that would most likely be the cause.