Don't know if these are similar but, on earlier bikes there is a thrust washer under the alternator/flywheel that can get displaced slightly when fitting especially if fitted in the bike so upright as it can fall from behind the flywheel and not be seen. Then, when torqued up it is trapped but tightens OK only to then move after it's been running a while. I had an ST2 engine in which I found a piece of said washer in the sump and the flywheel was wobbly, after the washer had broken away.
That's the one, quite a common fault I understand. Need to make sure it's stuck in place - use grease if engine upright or better yet engine on it's side and gravity holds it down.
I’ll check the parts Diag and check physically once I’ve removed the flywheel. That’s a job for another day, got to put it to one side for now.
The owner shared this photo with me from before I collected it. This, coupled with the unnatural noise from the LHS crank cover, plus all the filings on the sump plug, is what sent me down the path of possibly the coolant impeller shaft bearing(s) having failed and started to break up, along with the ceramic seal thus coolant was getting into the oil. However, it turns out that was just condensation as the oil and coolant when drained were as clean as if they’d just come out of their respective containers, which they had, <1000km ago, when it was serviced. Plus, there’s no evidence of emulsion in either the oil filler cap or the rad cap - so all a red herring.
We've all said that the nut looks like it's been rubbing on something, but actually having found an image of one they all look a bit like that: It's difficult to see from the images, but could item 11 be missing? Item 3 looks like it's there.
I’d say item 11, the thrust washer, which comes in different thicknesses is this, marked in red. There’s no apparent reason why the flywheel would have been off in the past and certainly it didn’t look as though the alternator cover had ever been removed since it was installed in the factory.
I love reading threads like this. Not because I enjoy the misery of others and their bikes, but because I love watching, listening and hopefully learning from them.
Well if anyone can offer words of experience it helps guide me and if it can assist others in the future that’s great too.
To continue. After being away travelling for a couple of weeks (WDW26 amongst other places) I finally got back to it today. Nothing. Absolutely nothing untoward under the flywheel. The roller bearing is good, the starter clutch is good, the washer behind the roller bearing is good and was in place, the woodruff key is in place and intact, I can see absolutely nothing that looks worn or is breaking up. The only thing I could find that didn’t seem right was that 3 of the 6 splits in the castellation of the flywheel nut had something lodged in them. On extracting it, I’ve no idea what it is/was. It feels hard and metallic but isn’t ferrous and magnetic so obviously nothing to do with the filings on the sump plug. NB the flywheel nut was definitely done up to the correct torque so it wasn’t a case of it coming loose and causing vibrations along the crankshaft. A visual check of the main LHS crankshaft bearing while it was exposed didn’t indicate any damage to that either. I’m at a loss as to what was causing the unhealthy noise. If it were big end bearings they wouldn’t be magnetic and stick to the sump plug.
i got reminded of this again the other day. first time two up in a long time. first time on a bike proper for a long time tbh. the weirdest noise ever under acceleration. you would swear blind it was big end related. very loud and vv worrying. so much so, i took it to the dealer to have it checked. understandably, they couldn't recreate the fault. i've decided that the noise is coming from the exhaust (cat) mounting under the engine. the gromet the mounting bolt goes through is slightly off line and worn through to the collar on the bolt. it is rubbing on the bracket under (checks over shoulder) heavy load.
Is there not any indication at all that somebody could have been in there before? If they repaired something and didn't clean out all the debris some of it may have found it's way back into a position where it caused the noise. And of course it's not completely unheard of for there to be a spare dropped washer or circlip floating about in the engine from the factory.
