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Discussion Starter · #1 ·
I mentioned this in my project thread and thought I had fixed it but the noise is back.
Bike is a 1982 CB450SC with an 85 emissions engine.

Here's what's going on: At higher revs (5-6K+, guessing as I don't have a tach), when I let off the gas I get a noise that is sort of a whirring sound that clearly sounds like a chain. I can't make it happen in neutral making it hard to listen for. I think I have also heard it under hard acceleration, but it's hard to say with wind noise and exhaust. There is not any excess vibration and when I swapped clutches I noticed the balance chain adjuster was at its limit, so I reset it one notch.

This first started after I laid the bike down at about 10 MPH. Last tuesday I manually adjust the cam chain tension by loosening the acorn nut, pushing down on the intake side cam chain tensioner and tightening the acorn nut. This made the noise go away completely, but only for about 100 miles. The noise is now back. By keeping the revs low and short shifting I have been able to keep the noise to a minimum, but that isn't a solution.

I have the day free and here is my plan:
  • Change the oil and filter
  • Check valve lash
  • Once again manually adjust cam chain tension

When I have the valve cover off I will try to see if anything looks out of whack.
What could be the cause of this noise? And what should I be looking for? Has anyone encountered something similar?
 

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It might not be your camchain; it could be the balancer chain; little slotted cover; undo the locknut and do it up again; it’s self tensioning.
 

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Discussion Starter · #3 ·
I adjusted the balance chain, cam chain and checked valve clearance. The noise is now gone again. I'm still skeptical that it is gone for good.
 
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