'78 Honda CB750k

[2ndRate]

My bike recently started making a rattle/ metal churning noise near/around the top end of the motor. Any thoughts? Thx.

[Re-run]

What where you doing when this happened? Have you checked your oil for metal particles? I hate to say this but the safe thing to do, not just for your bike but yourself, is to pull the engine out and take the valve cover off and check things out.

[2ndRate]

I put it in the shop-was told it is the timing chain. only has 25,000 mis on it. They adjusted the tensioner and said it quieted down a bit, but still making noise.

[CB750Winger]

   You may want to check the chain tension again. It needs to be on the right stroke and tensioner working free. It might have been sticky. The clutches on these bikes often make noise too.

[2ndRate]

Ok will do. Thx for the help/suggestions.

[Re-run]

Remove the 3 bolts for the tensioner and pull it off carefully. If you do not tear the gasket, you can reuse it.
now hold your hand over the opening and loosen the bolt there. the tensioner should push into your hand. If not, it needs to be pulled out and cleaned. Oil gunks up in there and can cause it to not work right.

I never asked but does the noise lessen if the clutch is pulled in? If so, then you are in luck hopefully. A carb sync would be in order.