THE CFI WAS CHECKING OUT A PRIVATE PILOT. THEY WERE DOING STALLS WHEN THE PROPELLER STOPPED. THE AIRPLANE DID NOT HAVE A STARTER AND THEY TRIED TO GET THE PROPELLER WINDMILLING BUT WERE UNSUCCESSFUL. THE FAA REPORTED THE PILOT LANDED 30 FT. SHORT OF A 4000 FT FIELD WHICH COLLAPSED THE LANDING GEAR. ADDITIONALLY, THE FAA REPORTED THE CARBURETOR FLOAT WAS IMPROPERLY SET WHICH CAUSED AN OVERLY RICH MIXTURE AT VARIOUS POWER SETTING. THEY OBSERVED BLACK SMOKE COMING OUT OF THE EXHAUSTS BETWEEN IDLE AND 1400 RPM/