When I raced 100cc & 125cc air cooled 2 stroke flat track bikes in the late 60's, most other riders used pure castor, I used Klotz Super TechniPlate, which is their synthetic oil mixed with 20% degummed castor oil. I did not have half the problems other’s did with gumming up their engines, my one 100cc rotary valve Suzuki that only had a single ring just .040" thick, 1mm for you metric folks, never had a problem, ran two maybe three races before tear down. Klotz makes Great oils I'm using R-50 in my 49cc Zoom engine and 66cc Grubee mixed 25:1 break in and 32:1 after and it SMELLS Good. Think I’ll pick up a pint of Super TechniPlate next time I go down state to try out in my 66cc and see how it works. I did pick up an oil safe empty 2oz plastic liquid bottle from my druggist to use for those emergencies, thanks for the great suggestion.
Mike