WHILE RIDING THE MOTORCYCLE AT CITY SPEEDS, ANOTHER RIDER ON A DIFFERENT MOTORCYCLE RIDING BEHIND ME, INFORMED MY THERE WAS SMOKE COMING OUT FROM UNDERNEATH MY MOTORCYCLE. I PROMPTLY TURNED OFF THE ROAD AND SHUT OFF THE BIKE. I ALSO LOST 100% OF MY REAR BRAKING ABILITY. I IMMEDIATELY SMELLED SOMETHING BURNING AND HAD SMOKE COMING UP MY RIGHT LEG. I GOT OFF THE MOTORCYCLE AND NOTICED 6" FLAMES COMING FROM UNDERNEATH THE MOTORCYCLE. I TRIED TO BLOW OUT THE FLAMES AND SMOTHER IT WITH MY RIDING GLOVES, WITH NO LUCK. ONE OF THE OTHER RIDERS IN THE GROUP HAD A BOTTLE OF WATER AND WE QUICKLY EXTINGUISHED THE FLAMES. AFTER FURTHER INSPECTION, THE REAR BRAKE LIGHT SWITCH WAS AT FAULT, CAUSING AN ELECTRICAL SHORT AND FIRE OF THE WIRING HARNESS AND INSULATION AS WELL AS ALL LOSS OF REAR BRAKE HYDRAULIC PRESSURE. THE FIRE CAUSED SIGNIFICANT DAMAGE TO THE SURROUNDING ELECTRICAL WIRING, INSULATION AND LOOMS. I CONTACTED HARLEY DAVIDSON AND THEY SAID THEY HAVE "NEVER HEARD OF SUCH A THING" WHICH I FIND IRONIC SINCE 1000'S OF RIDERS, ON LINE, HAVE EXPERIENCED THE SAME AS WELL AS HARLEY ISSUING A RECALL ON THE SAME SWITCH FOR LATER MODELS. *TR