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2006 150TXR 2 Stroke overheat

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  • 2006 150TXR 2 Stroke overheat

    New to me motor that sat a year before I installed it. Has good compression, runs great in a barrel but it seemed like it was running hot so I gave it an extensive vinegar treatment to try to remove excess salt buildup. New waterpump installed.

    Ran the boat in the bay and my suspicion was confirmed, tach gave the overheat horn after 15 minutes at 4000 rpm. Did some research and after checking thermostats and poppet valve I pulled the head covers and heads.

    Extensive salt/calcium buildup around the cylinders, passages and inside head covers. Cleaned everything up, confirmed no blockage by dropping lower unit and running hose up the water tube the water pump meets. Water flow is great, water pours nicely out of top of heads with thermostat covers removed.

    Run the boat over an hour at varying cruise rpm's with no overheat. Problem solved, but...

    I have always heard you should be able to rest your hand on the head of a two stroke without it feeling scalding hot. I've owned 4 other 2 stroke yammies and don't remember any of them feeling this warm.

    Starboard side seems normal, can rest your hand on it comfortably for several seconds. Port side, scalding hot. No more than a second or two.

    So, no alarm, but the engine FEELS warm. Am I overthinking this or is there something else I should look at?

    I've ordered new thermostats just to be sure and pulled the inner and outer exhaust cover just to verify no blockage, was some salt build up and carbon buildup but nothing major. waiting on new gaskets.

    Sorry for the novel, anyone have any insight as to how hot this engine should feel?

  • #2
    I would have tested the stats to make sure they operated in spec just to see if one had a problem


    • #3
      I did. Put them in a pan full of water and heated it up. They both opened roughly the same time, water was around 160 iirc, been a month since I did that.

      When your motor has run for a while can you comfortably put your hand on the head cover or is it too hot to touch?


      • #4
        I do not know for sure, I have not tried that on mine.
        seems I have read large motors one side will be hotter than the other


        • #5
          Just to follow up, after cleaning up the inside of the engine exhaust housing and installing new thermostats I ran the motor yesterday for over two hours with no issues.

          Most of the time was at 3800-4200 and I came off plane every half hour or so and took the cover off to feel the cylinder heads.

          As I remembered from previous motors, I could comfortably hold my hand anywhere on either cylinder head and thermostat cover. Very warm but not scalding hot to the touch.

          Motor runs perfectly, that problem is solved. Now to fix the kicking up in reverse and adjust the idle, 500 rpm in neutral in the water is a bit low.