2004 Yamaha FZ6

Front drive shaft, chain sprocket ‘Nut/lock washer’ has came loose and fell off on the highway. Could have locked the chain around the wheel and cause a major crash, also could have severely damaged the engine casing. It damaged the rear swing arm and a piece piece near the stater. I replaced the nut & locking washer tab, exact replacement only To have the same issue just I didn’t allow it to spin off since I was aware of this happening. I replaced the second one with a different style but same locking washer tab same issue it comes loose within 8 to 10miles. The nut is torqued to spec as stated by Yamaha. Iv reached out to several places including Yamaha and cannot seem to find a solution. Iv joined motorcycle forums and read people with same issue I’m having and wow am I lucky one. But they have had replacement parts and labor performed because of a safety recall of the issue. Why can I not get this resolved I have no clue what els to do.!! Please help

THE MOTORCYCLE HAD PROGRESSIVELY WORSE STALLING AT STOP-LIGHTS AND STOP SIGNS. AT TIMES THE MOTORCYCLE WOULD STUTTER AND STALL WHEN TRYING TO INITIATE THE THROTTLE FROM A STOP, AND AT OTHER TIMES THE MOTORCYCLE WOULD RANDOMLY INCREASE SPEED WHILE CRUISING ON THE HIGHWAY. THE THROTTLE BECAME QUITE VARIOUS TO THE POINT IT WAS NOT SAFE TO RIDE IN TRAFFIC DUE TO NOT KNOWING HOW THE MOTORCYCLE WOULD REACT TO DIFFERENT THROTTLE INPUTS. IN ORDER TO FIX THE PROBLEM THE THROTTLE POSITION SENSOR HAD TO BE REPLACED. *NM

BIKE STALLS WHEN CLUTCH IS PULLED IN. RPM'S DROP TO ZERO. WAS ALMOST RUN OVER BY TRAFFIC BEHIND ME WHEN ENGINE STALLS. INJURED MYSELF (FOOT/ANKLE) WHEN TRYING TO PUSH THE BIKE OFF THE ROAD (SO I WOULDN'T BE RUN OVER). I'VE BEEN TOLD BY MANY FZ6 RIDERS THAT MANY OF THE FZ6 BIKES HAVE DEFECTIVE THROTTLE POSITIONING SENSORS (TPS) AND THAT YAMAHA HAS NOT RECOGNIZED THE PROBLEM. I BELIEVE IT TO BE A VERY SERIOUS SAFETY ISSUE. SOONER OR LATER, SOMEONE IS GOING TO GET RUN OVER BECAUSE OF THIS DEFECTIVE SENSOR. *NM

1. BIKE WAS BADLY HESITATING STARTING OFF IN 1ST GEAR FROM A STOP. 2. TURNING THE THROTTLE TO ACCELERATE WOULD SOMETIMES PITCH ME FORWARD ON THE START AS THE ENGINE HESITATED, THEN TURNING IT A BIT MORE WOULD ALMOST THROW ME OFF AS IT ACCELERATED. 3. ONE DEALERSHIP TRIED ADJUSTING THE THROTTLE POSITION SENSOR (TPS) AND IT ACTUALLY MADE THE PROBLEM WORSE. THE NEXT DEALERSHIP REPLACED THE TPS UNIT AND IT HAS BEEN RUNNING FINE SINCE. *AK