Engine Noise...
 

I have an engine noise that has developed and gotten worse since I have owned the ATV. It is a 2001 Polaris 500 Sportsman 4x4. I have had to do a lot of up keep on it. From replacing axles, fixing reverse indicator switch, bleeding the cooling system of air, rebuilt the carburetor, and replaced the starter. There is much more I have done, but this is the bases of it.

The ATV sat for awhile waiting for me to install the starter, when I finally did I did not remember the noise from the ATV previously. I am not sure if it is in the top end as in it needs the valves adjusted or if it has something to do with the Bendix/starting assembly or the recoil starter. I would like to isolate the problem before I put anymore time into it trying to diagnose the problem. Below is a video of the noise. I did not replace the Bendix when I replaced the starter, which tends to draw me to that conclusion. I still need to dial the carb in as far as tuning goes but it runs like a scalded dog otherwise. The noise just gets worse with more RPM's.

Any help or assistance you can give on where to start would be greatly appreciated! Thanks.