I have a 78 mercury 115hp 1150 i cant reach 5000 to 5500 rpm ive tryed 3 props started with 21 and went down to a 17 the most rpm at full throttle iv been able to get is 4400 i know my motor should get up to at least 5000rpm. its on a 18ft 1969 stylecraft speed boat i wanna use it for wake...
