Monday I rode my motorcycle to work. That is not anything out of the ordinary. What was out of the ordinary was the smoke I saw coming off the motorcycle when I parked it. There was some fluid dripping onto the exhaust pipe and then burning off. Not being particularly savvy about the internals of my motorcycle, I noted the color of the fluid (blue/green) and location of the drip and figured I would ask around.
That afternoon, I got one of the other engineers who used to own the same model motorcycle to come look at it. The fluid was coolant coming out of an overflow hose. We checked the reservoir and it had plenty left. So the other engineer pretty much shrugged and said, it happens some times. I wasn’t particularly convinced by any of the plausible scenarios – the reservoir hadn’t been too full because it had not been filled for a number of rides. I didn’t think it would have overheated since it was below freezing for a good part of the ride in. In any event, it looked safe to ride home.
On the ride home, I did not notice anything special. I usually drain the carburetors every time I park the motorcycle for the night because they gunk up with ethanol if I don’t ride the motorcycle for a week. Some times I remember to turn the gas switch off far enough out that the engine putters out not long after I arrive, other times I forget and have to wait a couple minutes. Monday was the latter case. As the engine was puttering out, I heard splashing on the floor and saw coolant pouring out. The temperature gage read high, and I realized I was not hearing the cooling fan. So it looks like I need to go figure out what is wrong with my motorcycle before I ride it again.
First guess is bad thermostat.