[Kevin Mahoney]

You are getting good advice. Sometimes the clanging can be my own teeth.

[Mr.Mazza]

My jacket zips also rattle

[Kevin Mahoney]

The solution to many of these problems is a louder pipe

[Candoman]

I bought a new helmet, I can't believe how much quieter my bike is!  I can still hear the thumping from the exhaust but the valves are now only a distant ticking.

[singhg5]

The sounds on my bike have come from different sources at times.

- ignition key which is on a small ring with another key flailing & banging on handlebar.
- gas tank due to loose mounting bolt
- Another unusual place, inside the headlight nacelle ! The hard plastic connectors jumping up/down hitting the
   nacelle floor producing rattling sound !
- Ofcourse sometimes valve train noise (generally my G5 is pretty good).   

[heloego]

...keys jangling in the ignition switch...

+1 

[Desi Bike]

In disassembling my C5 I found that I have been missing the two short bolts for the stock torpedo that  are/were behind the triangle bit for some time. Maybe they are loose?

 

[mattsz]

This is fun!  I give you guys basically nothing to go on, and look at the scatter-gun list of suggestions I get!  Thanks all!

Many won't apply to me for various reasons, but you wouldn't know that (I don't have a key ring, for example)... I'll bring the list with me when I get into the search later today.

[no bs]

might check the rear brake lever bumper stop, they tend to rot, allowing lever to contact exhaust pipe.

[cstorckiii]

A squirrel with a tambourine nesting in your toolbox?

[Scotty Brown]

Nesting in the tool box....... Now that is funny ........

[motorman2whel]

When My Iron Bbl made that sound it was a loose lower rear engine/trans to frame bolt. The one on a IB that's almost impossible to get a nut back on after it ejects itself. Or it could be the loose nut behind the bars .

[mattsz]

Well, you're not going to believe this, but it was the squirrel!  But he didn't have a tambourine - he was wearing Morris bells.  Go figure...

I've gone down the list, and I haven't found anything amiss or loose.  Went for a two-day 350 mile ride, and never heard it.  So it's still intermittent anyway - I guess I'll just have to wait for further developments...

[barenekd]

My two bits worth. I don't think you're still running the stock pipe, are you? But, just in  case you are, the little screws that hold the heat shield on will make a little vibratory, buzzy noise occasionally. It was mentioned before, but is easy to miss.
I guess the only rattly experiences I had on mine were the heat shield screws, from the first time I rode it out of the shop going home. I heard it the moment I started the bike. I rode it home anyway, can't sweat the small stuff. I didn't find out what it as until I pulled the pipe to replace the muffler. I had a couple of hundred miles on it by then.
The other vibration s when the tank bolt loosened up. That was rather intermittent for awhile, too, but it got worse and lost the intermittence when I was out in the desert about 150 miles from home. Not a fun ride home, but detecting the source was pretty easy when I got there. The nut had dropped down into the little square boxes on top of the gearbox.

[mattsz]

Thanks, Bare!  EFI silencer, with secure small heat shield; fuel tank bolts secure.

For once, I'm going to follow the advice I've gotten here more often than any other: I'm not going to worry about it.