strange rattle from the engine

There is a clak clak intermitent sound coming from the engine area. Seems independent from the clutch being engaged or not. Goes for a couple of seconds, stops...comes again...and so on.
I've found something similar in this video from youtube:

https://www.youtube.com/watch?v=WGjeYJtfg5M

Is it the cam chain tensioner? is it the clutch basket? should I worry?
Apparently it's a cb500 common quirk? This has been going on for a long-ish time now, bike still works all right apart from this.

Thanks in advance!

ps: I'll edit it with some more details, seems a lot of the posts here are about noises

-noise comes and goes, intervals of seconds, it's not monotonous and continuous like with a failed main bearing. It's like a sewing machine giving bursts of 3, 1 or 5 'clacks'.
-it's a '94 model
-has over 40,000 miles
-had many previous owners (like 5 since it has been imported!) and no service history or anything like that.
-has been mine for over 5 years with no major problem... knock on wood
-can a full synthetic Repsol hurt it?

Sounds like the clutch basket's bearings, it's a known issue of all CB500, easily fixed. There's a guide somewhere here, can't find it, I'm on my phone.

Yeah, think is something involving washers.
Thing is I wouldn't hack it unless it really is going to be a problem. I don't mind the noise, if the bike is fine.

Sounds very like the symptoms of slop in the camchain tensioner. I've been through several tensioners in my 125,000 miles. See this http://www.cb500club.net/t1118-cam-chain-tensioner

If it doesn't go away when the clutch is pulled in then it's probably the cam-chain tensioner... even if it *isn't* the cam-chain tensioner, you don't loose anything by replacing it (other than time and money!).

thank you all for the replies!

I use the dave500 suggestion with washers.

My cb5(1994) has done only 16.000kms. Needed a good carbclean, noticed also that there where a missing small gasket in the pilot screw.

After that I shimsed up five of six of the springs in the clutch basket.....and now there are no rattle