hi,

I have a 99 thundercat, the temp never goes above 60 unless i'm in traffic on a hot day. I've replaced the thermostat but it has'nt made a difference. Does anyone know how to rest the 2 switches on the back of the of the thermostat housing. In this cold weather the temp gauge isn't moving, the radiator is warm which indicates to me that the thermostat has opened and i'm concerened that the bike is over cooling.

If the rads warm and the engine is warm then its most likely the gague or its wiring, my old man was a mechanic his entire working life and still calls them worry gauges.

One of the switches you talk of will kick the fan in, when the bike is a lot hotter than you think is ok and the other will feed the gague. Sort which is which in the workshop manual and then (don't want to pick a CDI/electronic plug by accident) simply earth them. One should bring the fan on, the other should send the gague FSD (full scale deflection) to maximum.

Hi,

Thanks for the response, the fans kick in at just over 100 if i leave it idling for long enough, so the the fan switch and temp gauge both work, maybe the temp sensor isn't accurate?

I think your sender is probably out then, 100 is a bit early for the fans to run, that would be more like 120. Remember the system is presurised so it can run hotter than water's boiling point of around 100.

The thermostat wont open till probably 90+deg to send water to the rad. You can see 100 being a little premature from that. Sounds to me like your gague is maybe 20 degrees off. This could be down to earthing or bad connections, even a weak sender unit.

Its only a problem if it bothers you, so long as you know what is 'normal' there isn't anything to worry about.