not a big foot, on a 20' smokerkraft fishing pontoon, had a 19 pitch 3 bladed prop and would not go over 4300 rpm, changed it out to an 11 pitch 4 bladed prop. Cleaned the carbs, had them adjusted by mech engine idles good, sounds real good running. Still will not go over 4300 rpm. Any ideas? Could I have a bad tach? It reads 0 with key on and motor not running. Just seems strange that I would drop that much pitch and not gain anything in RPM's it's running 13 MPH at wot, so I'm pretty sure the 4300 is right. Also does not seem to be running as hard with the new prop. (quieter when running)