On July 22, 1995, at 1010 eastern daylight time, a Cessna 172F, N157JW, sustained substantial damage during a forced landing near Wyandotte, Indiana. The private pilot and one passenger reported minor injuries. The personal flight, conducted under 14 CFR Part 91, departed Coshocton, Ohio at 0720 eastern daylight time, with a planned destination of Tell City, Indiana. Visual meteorological conditions prevailed and no flight plan was filed. During a telephone interview, the pilot rated passenger reported they were cruising at 2,600 feet mean sea level. The engine began to "pop" and the engine speed dropped to 1,400 rpm. The pilot switched fuel tanks. He pulled the carburetor heat to the on position and the engine speed decreased slowly. The engine did not recover. The terrain was hilly forest, with no open fields. The pilot attempted a forced landing in a small wheat field. He made a 50 degree turn to align the airplane with the field. The airplane impacted the terrain sustaining substantial damage to the fuselage, wings, and empennage. The wreckage was examined by a Federal Aviation Administration (FAA) Airworthiness Inspector. He reported no evidence of preimpact airframe malfunction. A compression check revealed compressions of 50, 55, 10, 66, 62, and 58 pounds per square inch on cylinders one through six respectively. During the check of the number three cylinder, air could be heard flowing into the intake manifold. The number three cylinder was removed and examined by an airframe and powerplant mechanic. He reported "considerable" carbon under the intake valve seat and scratches in the valve stem.