On April 11, 2006, at 0814 eastern daylight time, a homebuilt KR2S, N24065, was substantially damaged during a forced landing near North Andover, Massachusetts, following a partial loss of engine power while departing Lawrence Municipal Airport (LWM), Lawrence, Massachusetts. The certificated private pilot sustained minor injuries. Visual meteorological conditions prevailed, and no flight plan was filed for the local personal flight conducted under 14 CFR Part 91. According to a Federal Aviation Administration (FAA) inspector, the pilot built the accident airplane over a period of approximately 10 years. The airplane was equipped with a converted 1983 General Motors Corporation Corvair automobile engine. The pilot had not previously flown the accident airplane; however, it had accumulated approximately 17 hours of ground run time. During that time, the pilot found dirt in the carburetor fuel lines and fuel tanks. The pilot subsequently cleaned the fuel lines and fuel tanks. The pilot stated that the accident flight was his first flight in the airplane. During the initial climb, about 200 feet agl, the engine lost partial power. Specifically, the propeller rpm decreased from 3,200, to 2,300. The airplane was unable to maintain altitude, and subsequently struck trees in a residential area during a forced landing. The airplane came to rest inverted in the trees. Examination of the wreckage by the FAA inspector revealed approximately 2 gallons of fuel remaining in the airplane's 9-gallon header fuel tank. The inspector did not observe any contamination in the airplane's fuel or fuel filter.