Based on your performance loss also look at your plug if glossy black you may have lost the oil ring.
If you get rotation, open the crank oil, screw in the spark plug; but, do not attach the spark wire. Then put your thumb over the crank oil fill hole and give the starter rope a pull. You should feel a pull and push. Replace the oil fill cap and see if you can cover the exhaust with a thin card of paper. Again pull the starter you should see the paper pop away; but not suck back to the surface, (sucking back is an indication of a blown exhaust valve). If you can do the same for the carburator intake, (it should suck up tight), if not it will tell you if you have a possible head gasket failure.
I know a bit of a bother; but it reduces un-necessary work. If any of these fail try a bit of heavy oil in the cylinder, (about a teaspoon), if cold you should get a good compression at the spark plug hole, if it falls off after 5-10 pulls of the starter cord it is a sure sign of cylinder ring loss.
Oh as to your mix check the color, white/straw yellow not good... Should be either deep amber or gold with 87-93 octane, and green towards brown with 97-110 octane when mixed with brown/green 2 Stroke oil, if I recall my old av-gas lineman days correctly...