Just because it moves with the cylinder head off doesn't mean that the piston moves up and down when you are trying to start. If the pistyon is moving it will sound a bit like the engine is running, a put-put sound. If there is no such "put-put" noise your engine is flooded, I guarantee. It's taken me 20 miniuts to get started before when I was new to the engines. Try putting a small amount of WD40 in the fuel, and spray an ample amount in the intake manifold. Whats the temperature like when your trying to start.
BSA