I had a noise for some time, but not similar to what you describe. There was more of a higher speed whine/rattle and definitely appeared to be from the front sprocket area. Due to various issues, the bike still has a very low mileage, but I did loan it to my brother for a tour and I thought the noise was worse on his return. I thought the rollers on my chain were very loose despite a fairly good chain maintenance schedule, and both sprockets were still like new, with no discernible wear on them. I decided to change the chain anyhow, and this has definitely solved my problem. I'm not a very spirited rider most of the time, so I'm not sure why the original chain seemed to be so noisy, and the rollers so loose (quite loose when moved with an implement). The bike is spot on now.
On a side note, I would highly recommend the AFAM Easy Riv 5 Chain Riveting Tool for 520 525 530 Motorcycle Chains, Such an easy job to rivet the new chain on. I faffed around for a whole afternoon with different devices (Including a brand new breaker/riveter tool which was useless and destroyed the new link, necessitating purchasing another link) before I ordered this which performed faultlessly.