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Installation of coolant temperature sensor (doubt)

186 Views 1 Reply 2 Participants Last post by  NorthCust
Hi guys!

I'm going to install an coolant temperature sensor on my 2011 Yamaha YZF-R125. I promise to do a tutorial when it's done, but first I need to ask a couple of questions:

Firstly, what would be the best place to locate the temperature sensor? I think at the outlet of the engine block, as it is the hottest point, however, only the coolant would flow when the thermostat is opened. Would it be better on the radiator return?
Whatever the case, I can't tell which is which. Which would be the blue one (item 19, Yamaha reference 5D7E24820000), and which would be the red one (item 17, Yamaha reference 5D7E24810000)(picture attached):
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The second doubt is the diameter of the pipes. I can measure the outside diameter, but not the inside (I would have to remove the antifreeze, disassemble, measure... reassemble, and repeat the process when I have the adapter). Could someone tell me the inside diameter of these pipes to install the sensor.
I found a post from @NorthCust , where he installs the 18mm. Would this be the right one? The available sizes are:
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Once all this is clarified, I'll place the order and I'll start installing it. I promise to tell you the result!

Thank you very much in advance,

Best regards! :)
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a bit like this?

The 18mm seemed to work fine. It was a bit tight and I found that I was happier with the angle of the radiator slightly more "relaxed" .. i.e. I moved the lower two bolts forward a little which gave the pipes a bit more space but otherwise it's worked ok since installation.. It's a super helpful upgrade although I do think it's possibly more giving info of the coolant output from the cylinder rather than the temp of the coolant going into the cylinder... it's still been very useful though, and allows me to be thorough with my warm-up routine.

Also it turns out everything I thought I knew about when the bike gets hot, was wrong. When I'm flat out it's chilling.. but sitting at a traffic light for 2 mins and she gets hot...I guess this is why we test :)

I couldn't really see a way of feasibly connecting it on the input side.. .I think arguably you may be able to just take a signal from the temp sensor which is already there (i.e. the one the bike uses) but I didn't know enough at the time to be ableto tell whether my takign an additional reading from it might affect the reading somehow and I didn't want to mess with the bike's inputs are it was working.
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