850 timing chain marks under camshaft cover

[Brendan W]

Well I've got marks about 1mm deep fore and aft under the camshaft cover. With the 1 arrow on the head there is some slack turning the crank backwards and the chain lifts a little on the front of the exhaust sprocket which gets worse as the adjuster wheel is backed off and I can feel it pumping. The lock screw was about 1/8 of a turn or less backed out so I took it out to 1/4 turn,
So is the chain rubbing and I can't hear it or am I looking at an older event in PO land. I've just opened up some valves to about 0.09mm and think I can hear the difference - surely I'd hear chain noise.
Any tips on what has to happen to scratch the cover appreciated.

[tkent02]

I'm thinking we're going to need a few pictures. Chain noise sounds nothing like happy tappy valves.

[Brendan W]

The grooves are made where the chain enters and exits the idler. No pics sorry . The chain looks new. Everything seems fine except for the marks. The bike pulls like a train and the oil comes out clean. The motor has been apart - I'm wondering if that was the reason.

[tkent02]

Only a guess without seeing, but it must be damage from before. You have the locknut set with the set screw locked in the 1/4 turn out position, the tensioner is tensioning correcty it seems? If you are happy the cam timing is correct it must be good.

Still I'd like to see a picture.

[tom203]

"....The motor has been apart - I'm wondering if that was the reason"

Seems possible, maybe chain tensioner froze or was set wrong and some PO corrected and replaced chain to be safe.