Welcome from Washington State, hope you enjoy the site. I would suggest you go to the introduction section and introduce yourself to the form, if you please.
The compression releases work during start up only, so no, I would say your issue might be a rear tire alignment issue causing your drive belt to rub on your pulley or it could be a loose motor mount. I would start by checking your upper motor mount (Below the tank) since that one seems to loosen up at times. If it's not that then take a bar of soap and rub the edge of your drive belt with it and take a test ride and see if the sound is gone. If it is then you know your rear tire might be out of alignment.
Good luck...
