Seized Handlebars Stem/Fork Steerer

[npn]

Finally got to rebuilding my Schwinn S[9six] viewtopic.php?f=1&t=415629

The handlebar stem is stuck onto the fork steerer. I've completely removed the bolt from it with the wedge inside (pushing against the steerer) and it won't move. Soaking in PB Blaster now... Thoughts on getting it loose?

 

[hamster]

Keep pickling in your favourite dismantling lubricant (I use Plus-Gas) for at least a week. I would try to tap out the two halves of the clamp which should be a sliding fit in the stem.
You then need to shock it.
As the stem is aluminium, it will expand more than the steel steerer. I would mount it in a workstand or with the front wheel in, pour boiling water over the steerer end and use the handlebars to try and break it free.