Yeah, that is what I thought. Odd though, I never thought a water bubble in the water line could/would stop the flow like a faulty thermostat.
Speaking of thermostat, I have looked around a bit and the best price on a thermostat for this bike is like $30! I don't ever recall paying more than $15 for a freaking thermostat. Good grief!
It was $60 for the last one in my car. It's a whole 'unit' in the car, not just a little puck like the old ones. Hoses clamp directly to it and it bolts to the motor. Obviously the only part faulty was probably a little puck deep inside but... the days of serviceable vehicles are drawing to a close! It's the American way after all. "It's gonna cost $800 to fix the car, so, I'm just gonna save my money and buy a new $20,000 car instead".
These cooling systems are much smaller than an automobile system. An air bubble can get trapped and not allow it to flow. In a car, air escapes through the overflow tank. On our bikes, the overflow tank is at the bottom of the cooling system so that doesn't happen, it has to escape through the radiator cap as part of servicing!
I had a Mercury Cougar once, supercharged. There was a small bolt that had to be opened to expel air when replacing coolant. Lots of guys didn't know that and would have cooling system issues after flushing coolant. But, in fact, on that car, you had to open this little bolt and let it idle for a minute. On later models Ford put a plastic cap on the bolt and labeled it "remove before adding coolant".