I've recently noticed my water temperature gauge is bouncing around alot (like hit the peg below cold and bounce to above H). When sitting and idling, it's fine, works no problem. But when I get out and ride, it bouncing around. Seems to do it the most under load.

I flushed the coolant a few months ago and topped it up after a few km's to make sure there is no air in the system. It was overflowing into the reservoir. Bike doesn't overheat and the cooling system seems to work great (fan kicks in near H).

I never noticed it before, but I don't usually look at my gauges when I ride, so it could be one of those things I never noticed.

Ideas?

 

Could be a bad sensor.

 

I seem to remember that if you join the plug terminals from the temp sensor together with a short piece of wire that the gauge will show hot, which means the sensor is duff. Try it and see if it works! I used to do this on some of the cars I've owned in the past.

 

Pretty sure it's just a bad connection. The temp sensor is basically a temp variable resistor so when cold it has high resistance and low when hot. If you short the connector to the frame the gauge will shoot all the way to the max. First check your connectors, then the wires. Wiggle them around when the bike is hot and see if you can make it jump around.

 

Ok thanks for the replies all. I will dig into it this weekend. I am heading out tomorrow to look at a new sled to add to the garage.

Could the problem be voltage related? I suspect my r/r is on its way out

 

Actually man this is caused by bad grounds. Had that problem on my car and on my 954..... And both turned out to be bad grounds.

Mine was a ground behind the cluster, every time I turned my lights on the temp would "rise" But actual temp was normal.

 

Took a look at it today. The sensor seems fine. On a cold engine, I get about 300 ohms from the sensor to ground. When I grounded the lead that attaches to the sensor, the temp gauge went to 'over' hot. No bouncing about, even with wiggling various connectors. I put a 24 ohm resistor inline and grounded it again. Read about 3/4 hot, again, no bouncing.

Cleaned the connectors (were a bit dirty) and put it back together. We shall see tomorrow I suppose.

 

No dice. Still doing it. Checked the connection at the plug by the fuse box and everything seems clean and tight. I suspect a bad ground, but it looks like there are two connections other than the thermosensor. One to ground (Green) and one to +12 (Bl/Br)
https://cbrforum.com/forum/cbr-600f-...-color-144273/

 

Grounding the wire on the sensor is not how you check it. That's how you check the gauge and wire.

If you really want to check it, put it in water and check the resistances as it heats up. use a thermometer to watch what it is at temperatures around 180-230. What you are looking for is a steady drop in resistance as the temp increases. Any sudden drops or spikes is a dead spot in the internal resistor that the gauge is reacting to.

 

+1^ .