K11 Owners Group

michaelcurrin · Posted: Fri Dec 17, 2021 12:32 pm Post subject: Cam Chain Tensioner

Also posted on BMW MOA site

Long story but here is the short version, several weeks ago started maintenance on the 1993 K1100RS. Checked valve clearances and ordered the required buckets (or whatever they are called). Left the BMW tool in place holding the timing chain tensioner down in place while waiting parts.

Mean while life happened (heart attack)

Finally made it back to the shop, get the cam back in but not enough slack in timing chain to remount the sprocket to the cam. Look in the see the rod pushing down on the timing chain is bent at about a 45 degree angle. Took some doing but got it out, tried using a similar sized drill bit in the BMW tool but chain adjuster will not move.

Hoping to not have to pull the front cover because that will require removing the sidecar and it's subframe.

Any suggestions?

Thanks
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Mike Currin
20 BMW R1250RS
93 BMW K1100RS / EML Speed 2000
06 Ducati ST3
67 Triumph 650 chopper

Flying Duck · Posted: Fri Dec 17, 2021 3:37 pm Post subject:

So you used the BMW special tool to keep the cam chain tensioner depressed and the pin in that bent? Is it possible that you turned the center part of the tool too much when putting it in?

I haven't taken the front of a motor apart in a while but I'm pretty sure that you need to remove the front timing plate to "reset" the cam chain tensioner. I think the cam chain tensioner is designed to be "one-way" (up) so that once it moves up when some slack develops in the chain that it can't move back down.

But if you posted at MOA then I'd wait to see if Paul Glaves responds and see what he says.
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Scott_Anderson · Posted: Fri Dec 17, 2021 8:20 pm Post subject:

I can just about guarantee you will have to remove the front cover to reset the tensioner assy.
Having the cover off also will allow you the access to inspect the chain rail guide and chain lubrication oil passage at the same time.
It is possible for that oil passage to get blocked/plugged which eventually leads to more friction/wear of the chain causing it to stretch.
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