Flywheel

[Aethelric]

I could hear a noise from the engine which sounded like a chain rattling so I replaced the cam chain and tensioners. There did not seem to be anything wrong with the old ones.
I took it for a ride and the noise was still there.
When I got home and stopped the engine there was a clatter.  When I tried to start it again the starter turned but not the engine.
So, suspecting the starter I took it off.  It was fine.
BUT the flywheel was loose and turning freely and is obviously disconnected from the crankshaft.
I am in the middle of stripping it down to find the problem using nhmaf's excellent PDF on clutch removal.
Not sure what I'll find when I'm down to taking off the clutch, and I see there are all sorts of warnings about blocking the crankshaft when removing the flywheel.  I haven't found anything on self detaching flywheels though.
Has anyone else come across this?

[Barry]

I don't recall hearing of this problem before. Either the flywheel bolts came out or they sheared. There is confusion about torquing the flywheel bolts with some incorrrect published information resulting in excessive torque on the smaller size of bolt so shearing is a possibility.

Sometimes published torque settings have to be tested against common sense on what a particular bolt size can be expected to take. 

[Aethelric]

The bike has done 46000 miles, about 26,000 by me.  I have never been in there before, and I'm guess I will be the first person to lay eyes the flywheel since the bike was built in around 1984.
I recently rebuilt the bike which had stood for around 10 years but did not get as far as removing the clutch.   

[donbmw]

 I think what you have going on is the starter ring is slipping on the fly wheel. Haven’t really look at the fly wheels on our bikes but I think they are built in two pieces.  I have changed the ring gear on aircraft fly wheels. They are just a pressed on close tolerance fit. Heat the ring gear to have expand an slip over he fly wheel. I have had the ring gear spin on my Yamaha wave runner one time.

[Aethelric]

You may well be right, thinking about it when I moved the bit I could see it did not seem heavy enough to be a flywheel.
That would be better as it means that I can take all the precautions when replacing the flywheel.
I should be in there in a day or too.
You have cheered me up Thank you.

[Aethelric]

The ring gear has indeed become detached from the flywheel.  It seems to be held on by six rivets which have sheared.



Now waiting for parts, including the flywheel, to fix it. So glad I don't have to get in there and re-seat the shims.

[georgesgiralt]

I'm surprised by the amount of metal flakes around the starter opening.
Could it be that the starter motor has the wrong number of teeth ? Or was not meshing properly on the flywheel rim ?
Or was the wrong type altogether ?
I saw a lot of crud but not that much metal on mine when I went there ...

[Aethelric]

I'm surprised by the amount of metal flakes around the starter opening.
Could it be that the starter motor has the wrong number of teeth ? Or was not meshing properly on the flywheel rim ?
Or was the wrong type altogether ?
I saw a lot of crud but not that much metal on mine when I went there ...

The ring gear has detached from the flywheel and was free to rattle about and has taken a little of the casing away. The starter seems fine.

[mrclubike]

Do you know you need  to block the crank from sliding forward before removing the flywheel 

Also the fly wheel can go on multiple ways
So you need to set it to  OT before removing it and then put the new one on with the  OT marks lined up Without disturbing the crank

[Aethelric]

Thanks.
Yes, I originally thought the entire flywheel had become detached, in which case the crank would have moved.
The engine is now set to TDC and I am waiting for flywheel, stretch bolts and clutch let down bolts etc to arrive (in about a week).

[ged in oz]

I’ve had my clutch out this week to do the rear main seal and oil pump o ring and my bike has pretty clearly suffered the same issue at some point - you can see the ring gear score marks on the case at the bottom of this photo.

The clutch holding tool was a 10 minute job to knock up, but it’s a virtual necessity when getting 125nm of torque on those flywheel bolts.

[ged in oz]

*Flywheel holding tool!

The ‘81 and later clutch just backs straight off btw, rather than having to relieve the pressure, as on earlier models.

[Aethelric]

*Flywheel holding tool!

The ‘81 and later clutch just backs straight off btw, rather than having to relieve the pressure, as on earlier models.

Oh, I did not know that.  I could have been in there instead of waiting for the clutch lowering bolts. I'll be in tomorrow.

Thank you. 

[Aethelric]

Here is the problem
This is the flywheel:-


Looks OK, but theses bits are not supposed to come apart.

[ged in oz]

This might help:

http://www.bmwr65.org/YaBB2.612/cgi-bin/yabb2/YaBB.pl?num=1446449519