I have recently purchased a small (12') pontoon boat with a new 25 HP Johnson motor. After 8 hours of run-in I can only reach 4200 rpm at full throttle. I've checked that the carb is wide open at the full throttle setting. The Johnson handbook says this engine should attain its 25 HP at between 4500 and 5000 rpm. I'd suppose that the supplied prop (10 x 13) is not correct for this application but I can find no smaller pitched prop (say, a 10 x 10).<br /><br />Any advice? I'd like to have a bit more speed but am not sure if another prop would help. Also, I'm not sure if running the engine "loaded" in this way is detrimental.<br /><br />Thanks for any help.
