New noise that creeps me out - vid attached

[Atesz792]

Hi all,
so I was keeping up with traffic, slowing down, pulled in clutch lever at 4k in 4th gear, shifted back to 2nd, gave a bit of gas to match the revs, then released the lever, so RPM got to about 6k. At this point I heared a real frightening noise, like metal on metal. Since then, there's nothing new under that range, but if I rev her up to 5-6k the noise comes back.
It (at least to me) appears to originate from the exhaust itself, now the mic in my phone isn't that great, but it's clearly audible at around 0:16 in the vid. Do you guys think something might have shaken loose in my silencer or is it coming from the engine (and if so, I think I shouldn't ride it)?

[åsaka]

Is something loose in the muffler or is received and chafe. Loose nuts, wire, etc.
If so, knocking without the engine running if you hear chafing or rattling.
Really hope a simple error.
Good luck before running further

[BockinBboy]

If the sound is only in that range - I'd be looking for something loose.  That particular range is notable for resonating loose bolts - right about 5k, little lower if its something really loose.

- Bboy

[Atesz792]

Thanks for the responses guys!
Follow up:
It really was a bolt shaken loose. Moral of the story is check your bolts often on any twin, especially aftermarket ones.
The bolts securing my rear luggage rack got so loose, I even lost one from the left side, and one on the right wasn't far from that.
Hope I didn't lose it too long ago, think the weight I carry on it could apply some strong twisting forces on the subframe and the rack itself.

[BockinBboy]

Glad you found the source!  Once my frame sliders started loosening on one side - right near the engine and that thing resonated so loud it scared panic through my entire body while it buzzed me on the seat... I didn't realize it at first that was the cause, but after a lot of inspection it became obvious... I haven't really heard many others experience the loose bolt thing, but I purposely loosened others and they all resonated on my bike at around 5k rpm, even fairing bolts on the plastic - some are more noticeable then others is all.  I re-torque every bolt down at least once a year on bike now.

- Bboy

[bombsquad83]

I used to have a lot of trouble with my exhaust header bolts rattling loose after new exhaust gaskets.  I had to tighten them every couple of weeks.  After a while, they finally settled in, and I'll just check them once a season.

[yamahonkawazuki]

I used to have a lot of trouble with my exhaust header bolts rattling loose after new exhaust gaskets.  I had to tighten them every couple of weeks.  After a while, they finally settled in, and I'll just check them once a season.

yup after my gixxer wedge conversion and reinstall had same issue lol. annoying Eh?

[enrgizerbunny]

Am I the only one using blue loctite on everything I can?