I can't imagine that the nut is simply vibrating off (the thread would need to be non existent at that point). I suspect that the socket is "bouncing" back and forth (left to right) and impacting the nut, forcing it off the drive shaft. The only reason the sprocket doesn't follow it immediately is that the chain holds it in line. Also with a high tension on the chain it will act to pull the front sprocket into line with the rear sprocket.  It would be interesting to see a breakdown of speed, sprocket alignment and engine mount condition (loose or soft mounts would allow the engine to rotate anti clockwise, when viewed from above, under load changing the alignment of the two sprockets) on bikes that have lost the sprocket.

I understand what you're saying. One of the reasons I'm not too owrried is on both the sprocket nuts I've had they both seem to undo one/two threads worth but then never seem to get any worse. It seem like when the pressure is reduced there isn't enough deformation in the thread to allow it to jump again.
In order not to tempt fate though, I will check it this Saturday.

I check it from time to time and in the six year or so I've had the bike the worst it's been it about one or two turns loose.
Still pretty shite though. You'd have though Yam would produce an undersized nut to match the bad shafts

Got the tabs on my sprocket nut bent over correct but the nut still works loose - the only explanation is the threads are slipping over each other. Periodically I re-tighten it.

 
 

That's the idea, only thing is she won't go out on her own, hence we seem to be stuck with granny dating sites.

I think anywhere is better than foulups. I've never known them provide a good service, the work is generally poor and excessively priced.

I'll post back when I get round to doing it - may not be for a few weeks though.

Starter is starting to play up in the mornings so looks like it maybe needing attention soon.


Anyone done one of these? Any tips/gotchas etc


I don't think it's the motor - sounds like something jamming.

Couldn't see him - he was in my blind spot 


Sorry, couldn't resist.


He was probably a bit too close (less than the 2 seconds), but not excessively close.






He's not the only one mind - MOST bikers seem to do it, ride directly behind you. If I'm following a bike I offset myself so he/she can see me in the mirror.

Why is it that every time I get a bike following me the pillock always rides directly behind me in the blind spot?


I had a prat with a loud exhaust following me this morning, I can hear him but not see him, so I moved position in the lane so I could keep him in the mirror. Guess what, me moved as well. Moron.

Bin liner - keeps it 100% rain free.


Rainx was found by one mag to damage the anti-scratch coating.