I have a 1994 225 aquasport with a Yamaha 250 ox66. when I take off it goes right up to 5200 rpms.as I climb up on plane I pull back on throttle to keep it from going to 5800-5900.rpm. when I am planed off I have about 1/4 throttle that doesn't seem to do much except make noise.should I be higher than a 17 pitch. not sure what the recommended rpm is for this engine.i am use to 4 cycle.sounds like its gonna blow up.i think this boat originally had a 200hp and this maybe the prop from that motor. ( there was 2 of us in the boat and about 60 gallons fuel.)