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    Prop Selection on 85hp merc

    I need to purchase a new prop since the existing one is pretty beat up. The prop is on a '77 850 merc and is 13 1/4 with a 17 pitch. The motor pushes along a 20' smokercraft pontoon at 20mph @ 4500 rpm. I cannot get the motor beyond 4500 rpm. The motor is strong for it's age. The current prop...
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    1977 merc 850 timing sync questions

    I discovered that only cylinders #3&4 had spark. I could get #1&2 to get spark but had to rev the motor. The motor would not idle below 1200rmp. I performed resistance testing on the both sectors of the stator and they both checked out. I read on the CDI website that I could change the...
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    Mecr 850 ? idle problem 85 HP

    Hello. New member but have been researching on Iboats for a couple of weeks. I bought a boat a month ago that has a Mercury 850 outboard. It is the blue line with the thunderbolt ignition. The seller advertised it as a 1985 motor. My research showed this was a mid 70's motor. However, the...
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