Sprocket Nut

[NB6C]

I recently bought a '98 FZS600 and after a bit of investigating, it still has the original thinner sprocket nut.
What are peoples thoughts on this issue nowadays? Is it worth trying to change it if the old nut has held on this long or am I asking for trouble messing with it?
Cheers

[ekozelj]

There is no big story here, change it and you will sleep much more peacefully.

Nut and washer kit part number: 90891-10124-00
or
Nut only: 90179-18006-00
Washer only:90215-21290-00

[darrsi]

There was never really an issue with '98 models, and i think the 25 year time span kind of speaks for itself. I wouldn't go out of your way to change it until you need a new front sprocket, and as it's only a few quid now just swap it over then.

[fazersharp]

There was never really an issue with '98 models, and i think the 25 year time span kind of speaks for itself. I wouldn't go out of your way to change it until you need a new front sprocket, and as it's only a few quid now just swap it over then.

Yep I am with darrsi on this, I have long held a theory that has yet to be proved wrong that the 98 never had the issue. But definitely replace with the new wider nut when you change the sprockets and chain which must be any time now. How many miles has it done.
On the other hand it must of had the chain and sprockets changed and the owner just put the old one back on. In which case I would replace as you have no idea if they have put it back on with the correct torque and or thread lock

[Gnasher]

There was never really an issue with '98 models, and i think the 25 year time span kind of speaks for itself. I wouldn't go out of your way to change it until you need a new front sprocket, and as it's only a few quid now just swap it over then.

Wrong     I know of at least 4 that had issues, only one destroyed their output shaft though.  The others were sorted by application of the correct thread locker. 

[darrsi]

There was never really an issue with '98 models, and i think the 25 year time span kind of speaks for itself. I wouldn't go out of your way to change it until you need a new front sprocket, and as it's only a few quid now just swap it over then.

Wrong     I know of at least 4 that had issues, only one destroyed their output shaft though.  The others were sorted by application of the correct thread locker. 

And when were they, this year, or many years ago?
I think after 25 years of use we could probably hazard a guess it ain't gonna happen to his bike.

[fazersharp]

Years ago when this was talked about more it always seemed to transpire that 98s where the nut had a problem turned out to of had a new sprocket in the past somtime so had been taken off previously and most likely not torqued up correctly and or used the wrong treadlock. Saying a 98 does not have the issues,  it only refers to a factory fitted untouched 98 sprocket nut.
If the OP still has the same factory fitted sprocket then I would say change it for the wide nut when you do the chain and sprockets. If they have already been done then take doubt of the nut and replace with the wide one.
Yamaha themselves at the time said that 98s were not affected. 

 

[Frasier]

I did the first sprocket change on my '98 last year (@36 000 kms), when I bought it, the original sprocket nut was definitely on, and was rock solid.