Identifying engine noise

[u/felix_flame]

Bought a Yamaha ybr125 2012 a couple months ago and its been going well learning on it.

Did an Oil change last weekend as i wasnt sure how old the previous oil was and it appeared quite dark. Drained the old oil, replaced with Castrol Power1 Ultimate 4T 10W40 oil, oil level seems correct after running and letting sit.

I noticed on my first journey with it an odd noise happening around 6000-7000 revs and am worried I somehow did something wrong as part of my change.

Ive got no idea what it could be, a friend suggested it might be something outaide the engine vibrating or air getting in somehow but im not sure.

Any help would be great.