On August 4, 2000, at 1615 eastern daylight time, a Cessna 150, N6712F, piloted by a private pilot, sustained substantial damage during a forced landing following an in-flight loss of engine power near Eastport, Michigan. The personal flight was operating under 14 CFR Part 91. Visual meteorological conditions prevailed at the time of the accident. No flight plan was on file. The pilot sustained no injuries. The flight originated from Mancelona Municipal Airport, near Mancelona, Michigan, at 1545. The pilot stated, "I was 5 miles out (south) at initial call. When I came to enter left downwind for 27 I noticed an aircraft sitting on 4. I asked intentions, they told me 'they were leaving in about three (3) minutes'. I told them I would remain 'south' of airport by doing a 360 to allow them to depart. As I left I used usual procedures (carb heat off - full throttle to gain some altitude). As I made turn I returned to descent checklist and re-entered downwind for 27 as the aircraft left 4. All remained normal until I keyed the mike to call my base turn. Just before making turn my engine mis-fired as if experiencing carb ice and stopped producing power, it remained operating sporadically but I was not able to restart using standard engine-out procedures. Engine was out on downwind for 27 affording no engine out area ahead (torch lake) so I was required to make a 180 to 59M airport vicinity. 59M has obstacles (70-80 ft maple trees) on approach to 27 as a result I very carefully traced a route generally following a driveway roadcut as my intended path. Doing so, I was required to contend with powerline obstacles. Realizing I would not make airport property I deliberately altered my best glide and slipped away airspeed and deliberately put nose in dirt and brush, choosing to hit a wooden plank fence to prevent aircraft from entering busy highway (US.31)." The engine was test run with a reassembled carburetor and repaired propeller. The run revealed that the engine idled normally and produced 2,100 RPM at full throttle. One magneto was "noted as being rough." See appended FBO statement. At 1615, the Antrim County Airport, near Bellaire, Michigan, weather was: Wind 280 degrees at 5 knots; visibility 10 statute miles; sky condition clear; temperature 24 degrees C; dew point 12 degrees C; altimeter 30.07 inches of mercury. A carburetor icing chart, copied from a Transport Canada source, was reviewed. The temperature of 24 degrees C and dew point of 12 degrees C were applied to the chart. The intersection of those temperatures was in the "moderate icing-cruise power or serious icing - descent power" portion of the chart. See appended carburetor icing chart.