KDXRIDER.NET

The buzzing noise happens when high RPM goes back down to Idle. This is a new noise I haven't heard it before.

I dunno sounds like that exhaust bolt is tight but not tight on bracket and seems to shutter to the sound on video to me. For shits an giggles check that. If you look at the video Im talking about the expansion pipe at the kicker bracket. If you notice it seems loose in a sense. The kdx loves to rattle bolts loose it prefers mud Loctite

sounds like loose pipe bolts to me. for me, I loctite blue everything. every 2t I've had likes to back bolts out, even the bolts that hold plastic on the bike, and it never happens in the garage or backyard during testing, it's always on the trail.

+1 to loose bolt somewhere

maybe this is because I never see my pipe when im on the bike but doesn't it seem to vibrate more then it should ?
(look at the rubber mount doohickey and you'll see)

im sure they do vibrate because all those doohickeys on both my bikes are broken but it seems excessive to me...I agree on the loose exhaust/bolt

On mine it developed the same noise kinda a buzzing sound ! it ended up being the bushing under the rear fender at the fender frame mount !

Mine sounded like that after an enduro.It turned out to be a motor mount up front.The nut was gone.