Re: 100:1 Mix
I'm running same mix as Pablo too. A touch of castor 1 oz per gallon works wonders for protecting your engine and offers very little buildup or varnish.
I'm running Sig Castor oil blended with Castrol 2 stroke oil. All smiles as I abuse my engines to extort maximum rpms with my slant head, shifter kit, and tuned pipe.