I have a 1974 Johnson 25hp, model 25E74M, that has very little power under load. It's on a 14ft Monark flatbottom, and with just me and some fishing gear in it, I can only get to about 19-20 MPH (GPS) and if I take a friend, I can barely get over 10MPH. The load capacity and engine capacity is right in line with where this boat says it should be. I can even tell a noticeable difference when I have my 6 year old son with me(he don't weigh much). With any extra weight in the boat at all, I can't even get on a plain. I know I should be getting much better performance out of this motor because I've driven these kind of boats all my life and never had a problem getting around the lake. My neighbor has the exact same boat as me, with a 25hp that is just 2 years newer than mine, and we fly around the lake in his. One day we were both out fishing, and he flew by me on my right side, passed me, cut across in front, went be hind me, and passed me on the right again. He literally drove circles around me! I tested spark, and that is good. Do you think a carburator rebuild is needed? I tried it myself, but I don't think I did everything right (had a lot of left over pieces). What other things could lead to an engine losing power?
