whirring sound coming from engine?

the sound is kind of hard to explain, almost like a whirrrrrr" if you can imagine that. Doesn't usually occur during idle. I can't seem to remember it happening before I recently took off the valve head cover to check clearance. Any chance it might have something to do with compromising the gasket when I took off the valve head cover?

Thanks a million and one.

It depends on what engine you have,, put it in your signature line, that way it always shows. Just go to your profile which you can access at the top of any page here.
I started getting a noise in my 650 like that it turned out to be the top sprocket between the camshafts. Replaced that and it stopped. You didn't by any chance overtighten your camchain tensioner did you that could cause a noise too.
Ride safe

On mine, if the valve cover gasket is at all flaky, you will see oil being forced out. Never a doubt.....

Ya got me there! The sound did indeed start after I adjusted the tension on my camshaft chain. Would loosening my adjuster bolt allow the chain some more slack and I could start the process from the start? (hopefully getting it right this time) My Clymer manual doesn't give much detail about loosening the camshaft chain, only tightening the son-of-a-gun.

What year 650 are you riding? while I've ridden many different bikes over the years my 77 650 is only the second I've ever owned. I don't think I'd trade it for any other. I really lucked out coming onto it, I was in line to buy an old Buell and my apartment was burgled, thus a lot of money went to replacing stolen things. Then I happened upon a low priced, low mileage 650 (sounded waaaay too good to be true) whose prior owner (only it's second ever) took damn good care of it. Serendipity struck and I'm glad not to be the owner of a Buell today...

Looking at your signature line my question is rendered redundant. Though I have another: What exhaust was stock on the '78? Mine has a 4-1 Kerker which in my opinion ain't bad at all.

I have a 77 650C with a Kerker and in my opinion, there is no better sound!!

Stock exhaust was 4 into 2.