I have a 1973 50 hp seahorse johnson electric star, cable shifter. It fires right up and idles great. when i have it hooked up to the hose it sounds very good and powerful. compression in each of the 2 cylinders showed almost perfectly 153 on each. Problem is when i get it in the water i don't hardly have any power even on a full throttle. it will pick up some on initial throttle up, but not much more than a good idle at full throttle. I have had the carbs of and cleaned them, but did not rebuild them. Also when i first start up everytime it smokes like crazy. i have a good mix of 50:1. Could this be timing or carb problems??? thanks in advance.