The attached picture is from my single rotor PP engine after about 10
hrs running time. Most of the time was running at WOT and 6000RPM. fuel
flow was around 8gph.
If this an indicator of mixture distribution at ignition, what does it
mean? if anything. Has that been observed by anyone else?

Richard Sohn
N2071U

You got me. I have never seen anything like that.
What kind of oil are you mixing?

Paul Lamar


I am using 1.25oz/gal ECHO two stroke oil.

Richard Sohn
N2071U

Never heard of it :) Looks like coked mineral oil.

Mix a teaspoon full with a teaspoon of gasoline in a tuna fish can
and light it and let it burn. Tell me what you see. Better yet
take a picture.

Good 2 stroke oil will sparkle while burning and leave no residue.

Paul Lamar