THE PILOT EXPERIENCED A POWER LOSS SHORTLY AFTER TAKEOFF AND SUBSEQUENTLY EXECUTED A FORCED LANDING IN TREES. THERE WERE NO OTHER SUITABLE FORCED LANDING AREAS. THE OCCUPANTS COULD NOT OPEN THE SLIDING CANOPY AND HAD TO EXIT THROUGH THE WINDSHIELD. THE AIRCRAFT WAS THEN DESTROYED BY A POST CRASH FIRE. NEITHER THE PILOT NOR THE PASSENGERS COULD SAY WHETHER OR NOT THE ENGINE HAD COMPLETELY QUIT. INVESTIGATION REVEALED CONTAMINATION IN THE FORM OF GRIT AND LINT THROUGHOUT THE FUEL DELIVERY SYSTEM. IN ADDITION, IT WAS DETERMINED THAT THE FOREIGN MATERIAL HAD BLOCKED THE VAPOR RETURN ORIFICE IN THE CARBURETOR. THE SOURCE OF THE CONTAMINATION WAS NOT DETERMINED; HOWEVER, IT WAS NOT GENERIC TO THE CARBURETOR OR FUEL SYSTEM. IT WAS ALSO DETERMINED THAT THE AIRPLANE WAS BEING OPERATED WITH EXCESSIVE MAGNETO DROP ON BOTH MAGNETOS.