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I recently bought a used boat and motor and the motor needed a piston and crank. I replaced them and went over the engine inside and out. The motor now runs great, smooth, and easy start. The problem is it will only run 4500 rpm. I tried a smaller prop, compression is good, timing 6 and 22, carbs clean, and firing on all six. There is no surging or missing or higher rpm and then drop off, it runs to 4000 and 31 mph (24 ft cobia) for cruise and then for last 1/4 throttle almost no change. 4500 and 35 mph top. If I momentarily hit the choke at full throttle there is no slight increase and then drop off but instant rpm drop, no overheat and plugs look a little wet after running. Does anyone know or can someone check with wire gauge or letter drill and tell me what the hole size should be in the main jet (146)? I want to see if previous owner could have drilled out jets. or other suggestions.
Thanks, racedone.
Thanks, racedone.