RE: OK Cub .049 A
as with all the old motors 1/2A's included they really shouldn't be run on the modern fuels. Even today's new 1/2A's still recommend 25% oil and these are high performance jobs. The old Cub will be an old over the hill motor in short order if you continue to use 17% cool power. Use Omega if you must it at least has some castor but really not enough to extend the motors useful life.
Used a lot of Cubs in my youth while not the most potent they were always a snap to start as long as your battery was fresh. Same for the Wen mac's they really needed a hot plug or else you heard the old cry'When's it going to start....MAC.
Dennis