I have searched the posts, but the issue is a little weird...
Warm weather, went out for a 2 hour ride. Early in the ride, in city stop-go traffic, the temp elevated a little. Nothing major, about a tad over 3/4, but being a gauge watcher I noticed it fairly early, and kept the rpms lower. Fan did not come on, I don't think it needed to. Fan does work at least last time it came on it did. Added new coolant to top- up the resevior about 4 days ago. No leaks from the cooling system noted.
After am jaunt on the highway, it dropped. Later I noticed more heat from the engine on the right side. A little weird, but kept riding. The temp gauge was higher but again, not abnormal.
So we stopped a a park for a half hour, then to a store about 4 blocks away. When I parked I noticed white marks on the right side - it was dried coolant that had come out of the rad cap sometime during the ride (hence the heat on my leg!)
Now, the bike did not 'overheat' that I noticed, but it must have for it to boil out of the rad cap - or maybe it is a faulty cap? Like I said the fan was coming on normal the other day, and coolant was circulating....the temp was not up to red the day it 'boiled out'.
I plan to check the sensor, but i can't get a way to get a pot of boiling water out there. So likely the thermostat first. I don't think there is air in there the gauge does not get jumpy readings. After I noticed the boil over I filled the res back to the right level again later than night.