On May 21, 1994, approximately 1550 mountain daylight time, a Kelly Long EZ, N8JE, sustained substantial damage during a forced landing near Lindon, Utah. The Airline Transport Pilot, the sole occupant, sustained serious injuries. No flight plan was filed for the local flight, which had departed Provo, Utah, about 1520. The ELT functioned and was shut off by an FAA inspector at the scene of the accident. The pilot stated that he encountered serious vibrations while in cruise flight. He reduced the power and the vibrations diminished, added power again, and the vibrations recurred. He reduced the power and attempted a forced landing in an open field. The landing gear collapsed after touchdown in a hard landing in the short field. Post-crash inspection revealed that the piston top of number three cylinder was not moving in the bore. The cylinder could not be removed during the inspection, but the piston top could be pushed part way down the bore, and it then moved back near top dead center with engine rotation.