For those asking after the Gen 1 and Gen 3 equivalent parts, this will help.
The Gen 1 switch is a skinny thing that completes a circuit to ground. It is a thermal switch. When that circuit is completed the fan relay is activated and the fan turns on. It is mounted in the bottom tank of the radiator. It has an M10X1.25 thread. It looks like this:
View attachment 35012
The Gen 2 is a short, fat switch that completes a power circuit, just as a flip switch would. It is a thermal switch. It handles the power directly with no relay. It is mounted in the bottom tank of the radiator. It has an M16X1.5 thread. It looks like this:
View attachment 35018
This is the Gen 3 water temperature sensor. It is not a switch, it is a sensor that delivers a variable voltage signal to the ECU. The ECU decides when the fan comes on by energizing the fan relay. It is mounted in the top of the cylinder head. It has a British Pipe Thread that is almost the same size as a 1/16"NPT. It is the BSPP straight (not tapered) thread type and the sensor seals against the head on an o-ring.
It is not the same as the Gen 2 water temperature sensor, it just uses the same hole in the cylinder head.
It looks like this:
View attachment 35017
All of the OEM switches are expensive - ~$60. All of these devices have generic aftermarket equivalents that are inexpensive - ~$15.
Sounds like it would almost be easier to just install a fan switch for hot days.I doubt it, @daave. A sensor like that, designed for coolant, should be built to send in the range of something like -30*C to +120*C with a linearly varying voltage output from 10mV to 100mV*. That's not to say that there aren't similar sensors that are calibrated differently in terms of *C vs voltage. You might be able to find one that is in the same body, but the specs aren't readily shared on these devices because there's no reason to; they exist in the parts catalogs at the OEM level so that engineers can pick and choose, but those values don't find their way into user manuals or shop manuals.
If there was a reason to spoof the sensor output to make the ECU do something different it should be pretty easy to do, though. You'd just need a voltage divider to drop the voltage or an additive voltage circuit to increase the voltage. And you'd probably need to be able to measure voltage in at least the millivolt range, if not microvolt.
And to be clear, the radiator switches are not sensors. They are switches. The switches are operated by bi-metallic strips that are set to close the contacts at one temperature and open them at another. A sensor is a device that always gives out a signal, but it varies in accordance to the magnitude of some physical attribute, such as temperature, pressure, light, sound, etc.
*I made all those numbers up, but you get the idea. The water temperature sensor needs to send a signal of varying *C vs voltage across the expected operating range to tell the ECU what the temperature associated with some action is.
At what temperature does the red zone start?
q.v., Post # 34 above.Yeah, I didn't install this switch because I was concerned of it overheating, I just wanted to keep the bike in a more consistent temp range, and it will probably only ever be needed while idling. I actually wish the bike ran about 10F hotter normally