I would like to share with your readers a stuck piston remedy. Bill Cherry, a co-worker and I used a portal power pump to remove a Maytag piston that was stuck at the top of the jug. After trying a number of methods, I told Bill hydraulic pressure would work. Bill promptly produced the porta power pump. With various fittings we adapted it to the spark plug hole. Then we filled the jug with oil and started pumping. It wasn't long and the piston was out. If you run into a stubborn piston you will at least force the oil in the right direction.
If you have a four stroke with a stuck valve in the open position, you could make a stout steel plate to bolt on in place of the head. I recommend using extreme caution when using high pressure. Practice safety first, always.
Contact Clomer L. Woodin at 15 Main Street, PO Box 191, Garland, Pennsylvania 16416.