I am running a 1978 inline 6 116 on a 16 ft runabout with a 19 pitch prop. I am having issues with the motor bogging down, only when it is hot outside (90 degrees plus) and the water temp is warm (80 plus). I took the boat out a month a ago and it ran great, maybe bogging once in a two hour outing, in the cooler weather, 80 degree outside and 70 in the water. Now that it is warm and humid the motor struggles and bogs sometimes ( most of the time). I pulled the plugs while on the lake (after having problems) and all looked good except for the top one, i replaced it and continued, checked later and all the plugs checked out fine (ie not fouled). I rebuilt the carbs two years ago, completely, fuel pump, fuel filter, cleaned tank, new hoses. Could this problem be caused by overheating? It has been going on for about three years. It seemed that the motor was pretty warm, obviously it is hot outside, but not to hot to touch. I also suspect jetting but the plugs all come out clean, telling me that it is running correctly. Checked compression in the cylinders, seems to be fine. Not sure where else to look. Any ideas?
