Re: 50 HP Evinrude compression
80 PSI compression is on the low side. Should be over 100 and closer to 120 - 135. Before getting to carried away, decarb the engine as was suggested. SeaFoam and Deep Creep are the same product only Deep Creep is the spray version. It can be found at most auto stores and farm stores that sell auto parts. Your marine dealer may also have it but it will be more expensive (typically). Search this forum on how to do a Decarb. That removes carbon that may be causing ring sticking. When the engine loses power, immediately check for spark on the dead cylinder. You may have a coil or power pack going bad. Run a can of SeaFoam (not Deep Creep) in a tank of gas. See if that helps.