If you get the rear wheel safely off the ground and run the bike in a stationary location, can you generate the same noise/sound? If so, using a listening tube can help you zero in on the noise. Rolex is right, the front sprocket is top on the list of suspects. But I would include the chain (good v bad links, tension, and alignment with rear sprocket) as well as the rear sprocket (wear of the sprocket along with wear of the rubber pieces inside of the rear housing). If you have the tire off of the bike, while it is laying flat on the ground, if you grab it with two hands by the sprocket and lift, it should not separate. If the sprocket separates from the wheel then those rubber pieces are worn and need to be shimmed or replaced. All of the above create noise on acceleration and when under load. It's always great when you can locate and eliminate the noise by addressing one of these. Unfortunately, it is usually a combo. For example, if the front sprocket is worn and noisy, that means the chain and rear sprocket should be replaced along with the front sprocket all at the same time as a unit.In this You tube video the bike makes the same noudr mine does. Has anyone ever figured out what it is?
Thanks for the reply, that video is from a fellow in Australia I think. My bike makes the same loud knock as the white one.I think it's the key rattling on the handlebar.
Seriously though, besides that you are under revving the poor bike, lugging it at one point, the video doesn't prove it's your engine causing the noise. The noise happening in a certain rev range, indicates it's likely something loose, or something rattling under the tank or inside the plastic. Looking at the chain and sprockets is a great idea too. This may even come down to chain tension.
YesThe way I read it that is not his bike in the video it just a example from YouTube