On April 4, 2000, at 1804 hours mountain standard time, a homebuilt Muxlow Pitts S-1C, N27DM, experienced a loss of engine power after takeoff from the Deer Valley Airport, Phoenix, Arizona. The airplane nosed over during the subsequent off-airport forced landing. The airplane, owned and operated by the pilot, sustained substantial damage. The private pilot was not injured. The local area flight was conducted as a personal flight under the provisions of 14 CFR Part 91, and was originating at the time of the accident. Visual meteorological conditions prevailed and no flight plan was filed. The pilot reported that he departed runway 7R to the east. He continued heading eastbound, and about 2,500 feet mean sea level, he reduced the throttle from takeoff power. The rpm decreased to idle. The pilot applied full throttle and ensured that the mixture was in the full rich position, the fuel selector was on, and the magnetos were positioned to "both." The rpm did not increase. He turned left toward the airport and noted an open area in the desert. A forced landing ensued, which resulted in the airplane nosing over and coming to rest inverted. The terrain was rough, and the aircraft sustained damage to the landing gear, upper left wing panel, rudder, and vertical stabilizer. The pilot reported that following the accident, the throttle lever was in the full open position and the mixture lever was in the full rich position. He stated that when he manipulated the throttle handle in the cockpit, the throttle linkage operated. The operator did not provide a Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1/2.