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Thread: 85 hp top speed

  1. #1
    Seaman
    Join Date
    Dec 2009
    Location
    Naples, Fl
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    66

    Default 85 hp top speed

    Hello every one
    I was on the water today, and maximum boat speed 35 mph (1986 18 feet bayliner capri and 1987 merc force 85 hp outboard motor) . It is ok? tachometer show 2500 rpm, I thinks is wrong, because rpm going up, but tachometer still show my 2500 rpm. On the back side of the tachometer small switch with digits, what is it? Before was force 125 hp engine, I change motor, but nothing did with the tachometer. On what digit switch should by?
    Other question
    I hit the ground 2 times and broke propeller. Now I need new propeller but I do not understand how read propeller size, somebody could explain? for example propeller size is 13-1/2"- 17"- 15 what is it?
    After that (hit the ground) the engine began to overheat, i have telltale, watter goes through, what could be wrong? If i had sand in the cylinder head water do not go out from telltale? I have steam all time from 2 holes, but overheat sensor ringing only today, one time. (maybe it is smoke i dont know)
    If I remove telltale, motor will be colder? Can I run the engine without thermostat?
    Thanks for answers

  2. #2
    Chief Petty Officer
    Join Date
    May 2009
    Location
    Dallas area
    Posts
    461

    Default Re: 85 hp top speed

    What body of water do you boat on?

  3. #3
    Captain
    Join Date
    Mar 2006
    Location
    Cape Coral, FL
    Posts
    3,320

    Default Re: 85 hp top speed

    Around here they say we have two types of boat owners. Those who run aground and those who never leave their docks. When you run aground here it sucks a bunch of sand into engine and ruins the water pump. The engines won't cool properly until you put in a new water pump. Maybe you had same thing happen to you?

  4. #4
    Seaman Apprentice catfish hunter's Avatar
    Join Date
    Aug 2007
    Location
    Burlington, NC
    Posts
    40

    Default Re: 85 hp top speed

    Ya thats about the normal speed for that motor. That tach on the other hand needs to be replaced from what it sounds like. Should be reading twice that at wot! As for the prop the 13 1/4 is the diameter and the 15 is the pitch.
    1989 four winns freedom 160

  5. #5
    Seaman
    Join Date
    Dec 2009
    Location
    Naples, Fl
    Posts
    66

    Default Re: 85 hp top speed

    When I put the boat on the water, I forgot to remove water hose, is why motor overheat? I use boat in salt water. It is was my 3 rd time on the water

  6. #6
    Captain
    Join Date
    Mar 2006
    Location
    Cape Coral, FL
    Posts
    3,320

    Default Re: 85 hp top speed

    Quote Originally Posted by Pan84 View Post
    When I put the boat on the water, I forgot to remove water hose, is why motor overheat? I use boat in salt water. It is was my 3 rd time on the water
    I was trying to say above that when you hit ground in the ocean it is often a sandy bottom. If you hit sandy bottom then you need to replace your water pump impeller.

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