Temp vs RPM

[bmwstve]

My bike temp is normal when fully warmed up and at idle, but when I rev the engine the gauge -immediately- swings to the cold indication position and as soon as I let the revs drop back to idle the indication returns to normal. At cruising speed the gauge indicates a lower temp than what was at idle but I can get it drop even more if I if I open the throttle quickly. I have 61000 Mi. Any ideas?

[MikeERideWNC]

It sounds like your thermostat is stuck in the open position.

Or, if you have ever added water to the coolant and not used distilled or purified, the minerals in the water have eroded through the metal of the thermostat, which is allowing the coolant to flow freely.

[vernvernvern]

Could be the thermostat, but I'd suspect an electrical connection loose or corroded.
Water temp isn't going to CHANGE that quick during riding without the fans coming on.

At idle, over several minutes, it should get hotter until the fans turn on. If your fans turn on and the temp gauge says normal, then there is something wrong with the gauge or electrical connections.

An open therm won't stop you from riding, but a closed one will get your attention right away.

Hope you find the prob!

Just my .02's worth. :bmw: