my bike has a decompression mechanism on the exhaust cam and i was wondering if anyone knew what it is and what it does???

That is a good question i had the same one no one could answer it

The automatic decompressor bumps the exhaust valve a little bit when the bike is being kick started in order to reduced the force needed to turn the engine over.

After the engine has started, the centrifugal force applied to the mechanism which is located on the cam gear forces the button back in and the cam acts normally.