May be a glitch in the manual there.
From the factory workshop manuals:

XT600Z: M20x1 120 Nm
XT600E: M20x1 120 Nm
XTZ660: M20x1 120 Nm Use lock washer
XT660Z: M20x1 80 Nm ("Use the lock washer")

Andy

A friend has told me to do some maths/engineering/ on the thread dimensions and qualities to see what it should be able to handle, he recalls doing his up above 100Nm. But the last thing I want to do is mess up that thread! So I’ll do lots of research and see what I find . If anyone on here has tightened there’s above spec that would be great to know too.

As stated above ... the thread is exactly the same on those models.

motorang wrote: Mon Jun 07, 2021 6:05 pm May be a glitch in the manual there.
From the factory workshop manuals:

XT600Z: M20x1 120 Nm
XT600E: M20x1 120 Nm
XTZ660: M20x1 120 Nm Use lock washer
XT660Z: M20x1 80 Nm ("Use the lock washer")

Andy

Oh thanks for that Andy, just to clarify though, are you saying that it should actually be 120Nm for the 2008-2015 660 Tenere?

Regardless, I've pulled it apart and it has turned out that the nut is still tight! Which I'm not so sure is the best outcome. I now have no idea where the rattle is coming from. It sounded exactly the same, I'm fairly sure from the same area, and it had the effect of jerkiness between decelerating and accelerating and vice-versa - all the same symptoms as the loose nut.

Anybody have any ideas of what else it might be?

Just a recap of everything:

Engine knocking on 2009 Yamaha XT660Z Tenere with approx 60,000kms.
- Took it to the shop and they found the crank nut was loose, tightened to spec and loctited it.
- A year later the noise returns, so I found the nut loose again and tightened it to 90Nm and used loctite again
- 3 months later (now) the noise has returned. I've pulled the bike apart and the nut isn't loose at all, so the noise is something different.

- The sound is a knocking kind of noise, I believe from the right side of the engine. Listen here - https://uowmailedu-my.sharepoint.com/:u ... Q?e=gTjY6c

- The engine is jerky between that point of on-load and off-load, which is what led me to believe there was play between the key and keyway.

I've noticed a bit of freeplay between the clutch plates and basket (I believe that's what they're called) but I have little knowledge of this area. I spoke to a mechanic today and he said it was quite normal, but here's the video, could it be causing my issues? https://youtu.be/eLQ4W8wuO8I

So now I'm trying to figure out what the noise is, and fixing it before it destroys the engine.

- Josh

Would be nice if you could do a video of the engine so we can see & hear the differences as you move it around the engine Josh.

Mezo.

It’s apart at the moment but once I’m sure 120Nm is alright and I get the key machined, I’ll put it back together and hopefully won’t be able to make that video because the noise will be gone

I pasted over a range of engine numbers from a now defunct forum that highlighted a gearbox problem on 09 ym bikes, it MAY help to see if yours is near them...

OK I took a deep dive there as you seem to be hesitant

I am only sure for MY bike (1VJ) and for the numbers I stated from the manuals, mate.
Maybe Yamaha decided to downgrade the material on your model, god knows.
You could use some strong threadlocker (Loctite fluid) to keep the nut in place. There is stuff around which only will come loose when heated over 200 °C.

However:

If you look up max torque for 20x1 in steel, it is way higher, even in normal tensile steel.
This is from a German bolt manufacturer:
https://www.google.com/url?sa=t&rct=j&q ... -RovSyHy3s

For M20x1 it states 400 Nm in low grade steel.
This is the max value - min value is 7% less (which is probably why there is a lock washer)

Usually Yamaha uses high grade material for shafts etc and much lower grade for nuts, so they go first.
In my opinion 120 Nm are safe. And if something fails it would be the nut, not the shaft thread.

Looking at the nut itself:
https://www.cmsnl.com/yamaha-xtz660-199 ... /0016.html
https://www.cmsnl.com/yamaha-xtz660-199 ... 017020274/

That same nut with part number 9017020274 is used in a plethora of models, including every single XT600, TT600, SRX600 which all have 120 Nm in the manual.

E.g. XT600 1VJ: https://www.cmsnl.com/yamaha-xt600z-198 ... /0015.html

So, the nut can take it. The crankshaft is specific to the 660 cc models, I dunno about him.

I am following XT600 forums for nearly 20 years now, never have I heard of a stripped thread on the primary side of a crankshaft. But I came across hundreds of loose nuts ...

Andy

Absolute Legend!
You’ve given me great confidence, can’t wait to get it back together and never hear that knock again!
I’ve also just made my own key using key steel, it’s a much more snug fit, so there won’t be any play!
I think I’ll loctite the key in as well, to fill any gaps there may be, any objections?
The loctite I’ve got is type 263.
thanks again! Hopefully my next post will be a photo of me enjoying the bike!