Full choke? Take your air filter off and choke it with your hand too and see if you can get it going. Take your pilot jet out of and blow it all out again, happens... And set your air screw to 1.25 turns out for a starting spot. Some of them are more cold blooded than others.
Also, I have re-built and modified at least 20 of these for friends and family and the only oil injector that I had fail was bought from Ebay from a YT60 and the adjuster nut was loose. They don't fail unless someone ruins it by "improving it."