Here are some links to products that may help:   Aerokroil         Gibbs     

Muriatic acid and 50/50 mix of ATF & acetone have been used successfully, and/or you may prefer John Aylor's method:

Note: 750 requires 3/4 tap

stuckcyl.jpg (267340 bytes)

A variation:

This works pretty good for ones that are stuck real bad.  Tap the stud holes with a bottoming tap. 3/4" fine works good on h2.
dill and tap 3/4" bolt with a 3/8" fine.   Use at least two of the tools, but use of all 4 holes will get an even pull.
Sometimes a bit of heat really helps, too.



Here is another approach, especially good when the piston rings are seized to the cylinder:
Wheel Puller