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can anyone tell me if these plugs are ok. This is after 100hours and after running the engine at 3200rpm then chopping power so they don’t soot up on taxi. Wondered if the needle needs adjustment due to the sooty black colour. Thought it could be running rich. 

My fuel burn at 5100rpm is 20 litres per hour 

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  • Re: Spark plug colour

    by » 5 years ago


    I think you should do your plug chop at 5100 just use your brakes. But yes those look too rich.

     


  • Re: Spark plug colour

    by » 5 years ago


    Thanks. I’ll have to tie the tail down to do a plug chop at that rpm or she’ll tip on her nose! I was thinking she might be running too cold. My CHT runs at 80°c and oil is at 90°c (both at bottom of green) and sometimes even lower as it is winter here at the moment. I have taken the summer cowl flaps off which will increase temps. Thought I’d start with the easy stuff first.

    these are my temps. The farthest right is with summer cowl flaps on. Middle is winter cowl flaps on. The left is before I did any cooling improvements. This picture was taken in summer.

    I would say if I run with the winter cowl flaps at the present season here, my temps would look something like the right picture, which is much warmer than I get at present  

    23712_2_D3131AFE-1692-4960-87F1-2973773ED662.jpeg (You do not have access to download this file.)

  • Re: Spark plug colour

    by » 5 years ago


    I would like to have  the specialists opinion but for me, regarding to the temps you are good because all temps are in the green arc.

     

    In my understanding if your temps are in the green arc everything is OK.


  • Re: Spark plug colour

    by » 5 years ago


    Unfortunately CHT and Oil temps do not tell much about mixture. The CHT was a great thing to have when we had air cooled engines, with water cooled heads, does not mean much. Oil temps say more about your cooling system and radiator/oil cooler flow than mixture.

    The key temp for mixture is EGT, this will go up quickly as you lean off the engine the range is in the Rotax manual. There are others on the forum more experienced than me, but I would drop the needle one notch and see how the aircraft performs and the plugs look. Different fuels burn differently but again those appear rich.

     


  • Re: Spark plug colour

    by » 5 years ago


    My next move will be check the needle and maybe lean a notch


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