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2004/2005 Yamaha 150 2stroke question

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  • 2004/2005 Yamaha 150 2stroke question

    i have a Yamaha 150 2stroke that has been sitting for 10 years. It was not pickled, fogged or any of the other buzz words I have heard used before the last use. Are there any suggestions about how to bring the motor back to life? It has just over 200 hours on it.


  • #2
    I would want to open it up to look at the shiny surfaces to see if there are rust pits.
    Cylinders,bearings, crankshaft, etc
    fogging is done to help protect these surfaces when put away


    • #3
      I would check the gearcase oil.
      check that the flywheel rotated smoothly with the plugs out. if the above works I would replace the fuel pump and lines, clean the carbs,change the water pump light it off on 50/1 premix and see what happens.
      however most folks will simply try to start it and screw it up.


      • #4
        I would also squirt some TC-W3 oil into each spark plug hole and then rotate the motor five or six turns with the starter motor to help distribute that oil within the cylinder.


        • #5
          By opening it up are you talking about looking through a spark plug hole or taking the heads off?


          • #6
            Originally posted by Suncoastsd View Post
            By opening it up are you talking about looking through a spark plug hole or taking the heads off?
            I myself would have a look down in the cylinders and see if they are rusty or not. Tools for this are cheap now. Depending on what you see, proceed from there as per the advice already given.



            • #7
              If you decide to get a scope make sure the tip is small enough to go through the plug hole.


              • #8
                I was gunna say the same, and add do not turn the motor inspect all cylinders with a bore scope first.

                Find the cylinders that are half way in the bore that don't expose any ports, and one that goes down if you turn normally (or if they go up rotate the engine in reverse.) Just rotate enough to the bottom of the stroke.

                Now inspect that whole bore. What you see will be the upper cylinder that would have contained the original air, the place where the rings were sitting, and the lower bore that contained more air and more likely open to the atmosphere.

                What you see will determine what you do next. A good engine that has not suffered too much corrosion will show those three areas as shiny and much the same.

                If there are considerable differences then this indicates the engine has corroded internally and this will include bearing surfaces.

                A call will have to be made whether you dismantle the whole engine. If not, squirt plenty of two stroke oil around in the bores and past the carby's. Then rotate fully observing smoothness.


                • #9
                  This is an unturned for ten years, twostroke.
                  Just to add if it were a four stroke the "gamble" is greater as the camshafts and cams and followers/ rockers would have dried up.

                  Generally the getting of oil to these surfaces is also essential before turning.

                  I have a motorcycle that I intend to bring to life (start) after some years of inactivity. i am sure the bores and bearings would be OK. But I will be removing the rocker covers and rocker adjustment ports as you would do for adjustment inspection. Depending on what I see, I will oil all the surfaces, if not loosen the cam mounts to make sure oil gets through. Fortunately this is relatively easy on motorcycles, not sure the same with 4st outboards. I will also change the oil and filter, and depending how paranoid I am at the time, I may attach an external oil pump somewhere (probably at oil pressure switch) and blast for sometime.Maybe also up it's bum hole (sump plug).

                  Remember do as much as possible before engaging the starter and as Townsend said, turn carefully by hand at first. Most engine wear occurs at startup when oil is at it's least where it should be.


                  • #10
                    Thank you all for all of the info. I will check on an endoscope to see what the diameter is compared to what is needed. Some of the auto supply places also rent some tools. Another possibility.