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WOT during compression test? and couple other questions

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  • WOT during compression test? and couple other questions

    Hi,

    I read that I should wOT when doing compression test. I have a standard throttle contol handle where you push it forward to put it in foward and push it further to increase the throttle. I also know that I shouldn't crank an engine in gear, so if I WOT it during compression test, will it do any damage or will it be ok because it won't fire up? boat is a 83 16ft Invader with a 90 hp v4 evinrude.

    another question on electricals. One of the wires that connects between the main connector (sitting on the port side) and the terminal block(on starboard), its length is pinched tightly around the 2 banks of cylinder head( it's too short to route it below the heads). the wire currently is wrapped in insulation tape, I suspect the original vinyl tubing is already melted. what can i do about it? should I extend it by cutting the connector off of the terminal end and attach a section of wire to it, what gauge wire do I need? do i some kind of "marine" connector? I know I should rubber dip it. do I need to wrap it with those expensive heat-shrink tubing from west marine or just some vinyl tubing will do?

    thanks

  • #2
    Re: WOT during compression test? and couple other questions

    I read that I should wOT when doing compression test. I have a standard throttle contol handle where you push it forward to put it in foward and push it further to increase the throttle. I also know that I shouldn't crank an engine in gear, so if I WOT it during compression test, will it do any damage or will it be ok because it won't fire up? boat is a 83 16ft Invader with a 90 hp v4 evinrude.
    You do not have to. The engine should not turn over in gear. You can manually hold open the butterflies (carb) at the carburetors.

    You are really looking for the relationship of all four cylinders. THey should be with 5-10 psi of each other.

    another question on electricals. One of the wires that connects between the main connector (sitting on the port side) and the terminal block(on starboard), its length is pinched tightly around the 2 banks of cylinder head( it's too short to route it below the heads). the wire currently is wrapped in insulation tape, I suspect the original vinyl tubing is already melted. what can i do about it? should I extend it by cutting the connector off of the terminal end and attach a section of wire to it, what gauge wire do I need? do i some kind of "marine" connector? I know I should rubber dip it. do I need to wrap it with those expensive heat-shrink tubing from west marine or just some vinyl tubing will do?
    Just cut and splice the wire or replace it. It is probably 14 or 16 guage. You can buy heat shrink tubing many places.

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    • #3
      Re: WOT during compression test? and couple other questions

      On the compression test you need to remove all spark plugs and disconnect the coils. It can not start with out the plugs. The WOT is that the carbs are at WOT letting in the Max amount of AIR. That is all they mean. Don't WOT throttle it with three plugs in and the thing running on muffs or you will have parts to sell on Ebay.
      To get WOT all you need to do open the butterflies on the carbs manually.

      TPFB

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      • #4
        Re: WOT during compression test? and couple other questions

        You do NOT have to wot a two-stroke. That's four-stroke stuff. Two stroke cylinders are wide open at the bottom of the stroke and air pressure is normal atmospheric at cranking speeds. Opening the throttles does nothing.

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        • #5
          Re: WOT during compression test? and couple other questions

          I did the test w/o using wot. the readings were 125, 120(#1 and #3 on bank 1), 110, 110(#2 and #4 on bank 2). do you see problem? Strange, I'd expect bank #1 to be lower because it looks to be in worse shape(paint chipping, and a little discoloration, at least I think that's what it's. bank 2 is still very shiny and beautiful.)

          is there's an easier way to do the test? for each test, I had to climb into the boat, crank it, climb down, reset it, climb back in. CAn I just jump certain cable while standing next to the outboard(pls give details). fyi, to disable the ignition, I simply disconnected the kill switch.


          thanks.

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          • #6
            Re: WOT during compression test? and couple other questions

            Jump the starter solenoid. Large terminal that has the positive battery cable on it -- to the small terminal that has the wire from the ignitiion switch on it.

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            • #7
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              Re: WOT during compression test? and couple other questions

              Decarb and new thermostats should even things up.

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