I have a 2011 polaris sportsman 550 touring eps.

Purrs like a kitten when it starts. It also sounds normal when it is accelerating. When I take my thumb off the throttle after it has been accelerating or going at a constant speed, it sounds like there is rattling from the middle centre (though it could be from anywhere I guess) for a short time.

Is that a normal sound?

Edit....It is definitely not a grinding sound.

 

Sounds like normal drive line lash or ****** as some call it. You have to consider that power from the engine goes to the drive clutch then to the rear clutch,then to the gear case shaft and then to the driveshafts. There's a little slack between each point of power transfer that causes the noise.