I beg to differ with all the replays. I just finished the 4th year with my Yamaha 150 4 stroke. I use it for trolling. It has 1259 hrs on it. Not one problem and I haven't even changed the plugs. My previous boat had over 3000 hrs on a 150 Yamaha with no problems. I have a 22 ft boat and can troll down to .5 mph. Just my 2 cents worth.