I am kindof getting in on the tail end of your problem but have you pulled your plug and pour a small amount of fuel right into the cylinder and try it that way? I have had to do this before and it has always seemed to work. It will almost always fire and most times will draw enough fuel to stay running. I have also squirted fuel directly into the throat of the carb with decent results. If it doesnt fire with these methods I would have to look at the ign.
Jeff