ORIGINAL: Test005
When you spin the prop and keep open throttle there will pass fuel into the cylinder.
If in doubt, put the plane inverted on a plane stand and start the engine with the carb pointing up
You can also remove the glow plug and pour (very little) fuel directly in the cylinder.
I've never had to do this on anything other than a Cox .049 engine. Even with that, there was no need to remove the glow plug.