From MopedWiki

First method: (creator: Generic) 1) Remove the cylinder head. 2) Spray piston and cylinder walls withh PB Blaster. 3) Use a sledge hammer and a 2 inch wooden dowel to wack that sucker loose.

Second Method: (Creator: Eric P) Try this method only if the cylinder is stuck tight and the ports are closed off. 1) Take an old spark plug and cut the top off with a hack saw or dremel (all of the yellow parts in the picture).

2) Next, cut off the metal piece on the bottom and tap out the electrode out with a punch (again all yellow parts).

3) Then weld a grease fitting on the top of the metal part of the plug.

4) Next thread the new spark plug tool into the spark plug hole and place your grease gun on it. Pump away! The grease gun will generate a lot of pressure which will break the piston loose. Good luck! -Eric

Please add to this article with new ideas as they are learned