Solved: Buzzing noise

[Julian]

Last couple of times I rode the bike I noticed a buzzing sound when cruising at speeds above 50 km/h outside town. At least that's when I notice it because it gets louder as the speed increases. I thought it was the chain but it's only present with open throttle and stops when I close the throttle and starts again as soon as I open it so it couldn't be the chain, right? It's a buzzing sound like steel balls hitting each other really fast and it's pretty constant and getting louder with speed. It's not too loud but it gets annoying and I'm thinking it shouldn't be there. It doesn't seem to affect performance in any way. What could it be? 

Edited November 20, 2021 by Julian

[Triple Jim]

Try lubing the chain and see if it changes.

[Julian]

4 minutes ago, Triple Jim said:

Try lubing the chain and see if it changes.

I did only a few days ago and if it was the chain, why does it stop when I close the throttle? The chain keeps spinning correct?

[Triple Jim]

Loading the chain may change its sound.

[robbo10]

Clean chain? How is the chain slack? When powering the lower part of the chain is at its loosest.

[Zephyr]

Does the sound stop when you close the throttle or when you come to a full stop?  Have you tried to ride beside a wall to reflect the sound back to you?  This helps me if I am trying to pinpoint a noise.  Also have you noticed a change when pulling in the clutch going at speed?  This would let you know with decent confidence if it is the chain or not.  Other issues with the bike such as dropping/crashes?  Higher mileage?  Possible debris inside the front sprocket area?  Check the chain tension to ensure it is within spec, too loose can cause noises, too tight and you should feel that when riding.

[Julian]

Ok so the noise I was experiencing is almost definitely the chain. I didn't hear it for a while but I cleaned the chain last weekend and it became noticeable again. From my first post you can see that I first noticed it shortly after cleaning the chain last time. I think when the chain is squeaky clean the metal one metal noise is more noticeable. As it gets covered in grime it probably muffles the sound. 

I can only hear it when my left knee is away from the tank, when the knee hugs the tank it goes away. Remove the knee and it's audible again. It's also more noticeable when I'm leaning left, I thought it's because of the lean angle but more likely because I tend to extend the left knee outwards when leaning left. 

[Triple Jim]

Yes, that sounds about right.  What chain lube do you use?  When I put DuPont Chainsaver on mine it starts out quiet, and as the miles go up, the sound becomes more obvious.  It reminds me to lube the chain every couple tankfuls.

[Julian]

I use gear oil on the clean chain then wipe out every bit of liquid on the chain and sprockets. The chain is dry but greasy to the touch. Last clean and lube was 1, 000 km ago as per the manual, absolutely no issues with rust and it has seen some rain. The front sprocket area was clean as a whistle, I won't even check there next time. Minimal flinging on the back rim on the first ride, I wipe it off an after that I forget about the chain for another 1000 km.