2008 610SM. When I first got the bike new, I don't recall the fan turning on. I wondered if it was broken. Now, the fan turns on after sitting at a stoplight for a minute or two when the outside temp is not really that warm -- like 75 degrees. Do your fans turn on under similar conditions? I am wondering if there is something wrong with the cooling system, or perhaps something is causing the motor to run hotter. I recently changed the Engine Ice and put fresh Engine Ice in. I checked the thermostat. I also tightened the water pump impeller blade. Neither of these caused the cooling fan to turn on less often. The strange thing is the right side exhaust header is about 400C when it exits the motor, the left side is about 300C. Not sure why the left side is 100C cooler. The exhaut valves are good at 0.002. The last thing I tried was to remove the factory oxygen sensor, and put the 2.2K resistor plug in. That did not seem to get the cooling fan to turn on less often either.
The temp sensors seen to have a fairly high rate of failure. They only cost 15$ or so. If that isn't the problem you will at least have a spare. Your temp difference is puzzling.
My fan doesn't come on unless I'm doing lots of rigorous hill climbing on trails. All other riding never gets it to turn on. Sounds like something changed on yours, so maybe that temp sensor will fix it. Good lucK and let us know how it goes.
My fan comes on within minutes of startup if I just sit there, not moving. Doesn't matter what the air temp is. It's always been that way. It's a small cooling system and it relies largely on air flow to cool (everything), it doesn't have a large enough volume to disperse the heat soak without airflow. I'd be more concerned about the temperature difference between your headpipes.
What I meant is - should one for example bridge out the sensor switch to check it turns on? I cannot remember when mine last switched on and am now wondering ....
Sure, or you can just start it up and let it sit there idling a while. If it boils over before the fan turns on...Well...There's an issue.
Mine neither ---- only when I have checked valve clearance and let it run for about 5 minutes standing still --- my second 610te started up immediately when I started the motor. replaced tp sensor -- end of story ---
