I would really start to worry if the temp got over 250 or if you got home and your shorts where melted to your ***!!

 

I've never used a 'temperature gauge' on any of my bikes, and come to think about it I don't know many that do...

Never really worried about the engine temperature, even riding many thousands of miles each summer here in the midwest where 100+ degree days aren't that uncommon.

Can't say that I know of anyone that has had any 'heat related' engine problems, and you just need to use a little common sense.. Don't set with the engine running any longer than necessary, take it easy with the throttle in very hot conditions, keep good fresh oil in the bike, etc..

BTW, here is what I run in my bikes during the various seasons. If I put my bike into hibernation like a bear during the winter like many I'd probably just run the RedLine year around, but I also do quite a bit of riding during the winter...