THE NON-INSTRUMENT RATED PVT PILOT WAS FLYING FROM HAMILTON, CANADA, TO BERLIN, NJ AT NIGHT. HE STOPPED AT BUFFALO, NY AND RECEIVED A WEATHER BRIEFING WITH VNR (VFR FLIGHT NOT RECOMMENDED) DUE TO RAIN, LOW CLOUDS, AND FOG. HE DEPARTED VFR AND CONTACTED WILLIAMSPORT AFSS, RECEIVED AN EN ROUTE BRIEFING AND THEN MADE AN UNPLANNED STOP AT ELMIRA, NY. WHILE ON THE GROUND HE RECEIVED TWO ADDITIONAL BRIEFINGS, BOTH WITH VNR. HE AGAIN DEPARTED VFR AND CONTACTED THE NY ARTCC FOR VFR ADVISORIES. HE SAID HE WAS AT 3200 FT, HOWEVER NY CENTER SAID 4200 FEET WAS THE MINIMUM RADAR VECOTRING ALTITUDE. HE FINALLY CLIMBED TO 4000 FT AND DISAPPEARED FROM RADAR AFTER APPROXIMATELY 1 1/2 MINUTES. THE LAST FEW RADAR CONTACTS SHOWED A LEFT TURN APPROX TWICE STANDARD RATE. THE GROUND IMPACT SHOWED THE AIRPLANE IN A LEFT TURN AT IMPACT. WITNESSES ON THE GROUND REPORTED RAIN AND FOG. NO EVIDENCE OF A MECHANICAL FAILURE OR MALFUNCTION WAS FOUND.