You probably tried this:
Pour a little gas down the carb, then try to start. You might also give each cylinder a squirt of Mystery Oil, as it'll help bridge the gaps in the rings, and its nice and burnable too. I've always found pouring gas down the carb helpful to get a difficult engine to start. It gives you a starting point too. You should get a sputter, which is quite uplifting, I can tell you.
If you stick your hand over the carb when you crank it, it should still suck, even with leaky rings.
