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Piston is black and brown on

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  • Piston is black and brown on

    Been running 25:1 for safety. Recently went to 32:1

    wondering if I should be going 40:1 or 50:1 or what...this is what the exhaust looks like...

    Running the stock adjustable barrel carb.

    A few main questions:

    1. How does this happen?

    2. Is the cylinder ruined? It runs perfectly fine.

    3. Should I replace the piston and rings and keep the cylinder?

    Attached Files

  • #2
    Which oil? Castor 927 is highly recommended. It just looks like your current oil has turned into varnish. The rings themselves look rather clean.


    • #3
      I’d stay under 32:1, 24:1 is what I use. Also what oil is that? I run yamalube now b/c it’s relatively cheap. Switched from 927, didn’t like how 927 is prone to separation.
      *******Pedding since '02********


      • #4
        Running racing castor blendzall its from cycle you guys think carb just tuned too rich?


        • #5
          hard to tell if that’s scorching, but something doesn’t look right. It can be a plethora of things. Improper f/r closer to the top of the list.
          *******Pedding since '02********


          • #6
            I’ve never run any of mine too rich for long periods of time. The second I feel the motor stumbling over itself, I get off and lean up the a/f screw. I think if it were too lean we would see more scoring.
            *******Pedding since '02********


            • #7
              Looks fine, just dirty. Run a les rich oil/fuel mixture, but don't go below 32:1. You might need to lean out the carb a little in addition to reducing slightly the amount of oil in the fuel.

              If it runs though, the it's fine. 2 strokes are dirty, and many stock G43L's that I have seen look like that.
              Instagram: @base_cat