ok, temp dropped from 240 and is now down to 160 after fan switched off. Coolant dropped way down and I added more. Do you just keep adding until it won't go down then put the cap on it?That is strange Mt. 201 degrees is not extreme and that was on a restart when temps normally run higher.
"I checked it and it had overflowed coolant around the radiator. "
Are you saying it spewed from the cap ? from the recovery bottle ? from a seam on the radiator ?
The temp should be hot coming in the top and cooler (not cold) going out the bottom hose.
Depending on the answer to where it was spewing from, I am thinking you may have been a bit low on coolant and got some air in there and bubbled/ blocked & overheated OR , you could have dirty fins that are blocking the air flow ie : mud/weeds/seeds/snow either on the front or the backside of the radiator. I would fill it back up and let it run with CAP OFF with the radiator up as high as you can and let it purge. If you can stare into the cap hole long enough, you will be able to see that it has good circulation .....or not.. No other overheat history ??
One other thing, in all the years of working on Polaris engines, I have never seen a bad/nonworking thermostat.