My sprocket nut and washer have probably screwed up some French farm machinery as they both pinged off into a field at 110mph not far from St Quentin back in 2011, the local Yamaha shop did a nice job picking the bike up and fitting a temp nut as a get you home fix, a trip to my local Yam dealer where I bought the bike yielded a ' Don't know nothin' about that problem, sniff' and £6 lighter and the proper replacement thicker nut, no problems since I fitted it and I check it, a lot, quite a lot :-)