2002 Honda Rancher 350 Overheating?

Hi,

I own a used 2002 Honda Rancher 350. I decided to buy a Honda because I know they are known for their durability and power, for anything I would need it for. I always noticed that my legs would feel the heat from the engine, and I wanted to make sure my components weren't overheating, before I damage anything accidentally. I used my temp. gun to take the readings from various parts, they are listed below:

These are temperatures after around 30 minutes to an hour*

Cylinder: Around 280 Degrees F
Crankcase: Never exceeded 190 Degrees F
Exhaust straight out of the cylinder: ~600 Degrees F
Radiator: Around 150-160 Degrees F

The rancher did not come with a radiator fan because it is a 2wd version, but I ended up buying one to wire to a switch, I just have not gotten around to installing it yet.

Are these Temperatures normal? Should I install that fan? What temperatures would be dangerous for the block and cylinder? I use Marvel Mystery Oil in every fillup.

My machine might be running lean because of the change in ethanol levels over the years, but again, I am no expert, any help would be appreciated!

Thanks!