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The motor is a 15hp four stroke start fine runs but will not reach full speed. Feels like it is struggling,and it will not plane out with just one person.
Is this a recent development? Describe the boat it's on. I find that 15 four-strokes are equivalent in power to 9.9 2-strokes. I'd guess you have a fouled sparkplug, carburetion problem, too much prop, or too much boat.
