I have a polaris sportsman 500 H. O. 2005 I would like to know how hard it is to change the thermostat

 

Just remove the two 8mm bolts to remove the cover. Look at the position of the small hole on the thermostat. It should be facing upwards.Pull out the old thermostat,reuse the rubber seal if the new one didn't come with one and replace the cover and bolts. You'll have a little air in the system so after install remove the radiator cap and let the fan cycle on and off a couple times. Top off the radiator,replace the cap,top off the recovery bottle if needed.