make sure if you put anything down the cyl. (diesel fuel works pretty well too) you have the plugs out when you try and turn it or you may have a hydraulic lock,you can't compress the oil. Also make sure it is somewhere that if it does break loose the oil that comes out of the plug holes can shoot harmlessly into the air. My friend shot diesel all over his white living room ceiling from all 4 cyl. of a Honda 750four. On that note after he broke that loose he rode it for several years with no engine work ever being done,I was amazed.

I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!