My '63 Johnson 28 hp has good compression, recent carb overhaul, new ignition, but isn't delivering the horses. Symptoms include hesitation, slow revving, no increase in rpms from 3/4 to WOT, seems to like lean mixtures (1/2 turn from closed low speed, about 1/3 turn high speed), bottom plug is usually wet, unburned fuel/oil leaks from gearcase weephole after every run. Does this sound like a retarded timing or spark advance problem? If not, what to look for?
