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Say Shep - in an earlier post you mentioned

1879 Views 10 Replies 3 Participants Last post by  marshallf3
Both my CX have a nominal running temp at the cylinders of 85 Deg C +/- say 5% or less.

You also mentioned that you've got one of those IR non-contact thermomemters.

Any possibility, when you get a chance, that you could take a temp reading at the bottom of the radiator (by the exit hose) to see what water temp is coming out when the bike is running at what you'd consider to be around ideal?
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I'll do it over the weekend or soon
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I've just run one of my CX up to idle+.It's hard to get a really accurate figure because of variables.My 85 Deg C reading the heads was on a very warm summer day after a good ride so the whole bike was hot,if you get my drift.Just done some now and my heads,once the fan cuts in,are at 75 Deg C even and the ambient day temps are 16 Deg C.

Before the temp started rising above the nominal mark the bottom of the rad cores was between 60/65 Deg C.After the fan had kicked in and I let it drive down the temps the cooling pipe and rad bottom settled around 65/66 Deg C.

I'll try and remember to do some more after a ride as that will give a better reading of normal use,not just stood idling before a ride.
Thanks, this is exactly the type of information I need and, oddly enough, close to what I expected. In addition it would be nice to know the hottest temp you can read from the radiator at the same time. Might be able to "point and shoot" the upper radiator fins through the grille, bet we're going to find a reading of around 85*

I think you decided that since you've got some air space around your switch the actual water temperature going in would be around 10* or so higher than the 70* switch you're using?

I settled on the 75 Deg C one to allow for the difference between the engine and the rad.I have to be honest and say again that you are really complicating a very simple thing.

The electric fan is not meant to nor needs to regulate the cooling system.It is there,as in cars,as a device for cooling the system in adverse,warmer than air-cooling,conditions and stop the engine overheating in those conditions.

This simple circuit will do the job and can be tuned,

It really doesn't matter about the Hysteresis and that the above circuit is basically an,"On-Off" circuit(It will by the nature of component tolerances have some hysteresis anyway and the time it takes for coolant to move etc).

If it was set to switch the fan on say just before the middle of the temp gauge the fan will drive down the engine temps and then it would switch off.Yes it may switch on and off a few times in traffic but that's not a problem.As soon as the engine gets air cooling the Efan is then redundant.

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I did build that circuit and it does just behave like a switch.

I realize what I'm building sounds a bit complicated but it's easy enough to build and will have several advantages like an indicator that signals a fan fault or overheating as well as a remote temp gauge output for those popular dot/bar circuits. Besides that it's a gadget and I, like a lot of others, like gadgets. :)

I know.I forgot you are on a,"Mission"

Should be a great unit
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Actually "not moving but fan on" gives me a pretty good low point, apparently the CX is quite happy getting 65* water back from the radiator if the heads were still that cool. Do you recall what the bike's temp gauge was reading at the time if you still have one?

I'm getting very close to having this on paper as a buildable device.

I don't see as I can give you much more info.I think you have enough.I've just come in from a good ride and with engine coolant pipe obviously with the Thermostat open was at around 80/82 Deg C so coolant flowing nicely.Left bike idling and fan switched in and cooled engine down to just below the nominal mark as usual and the coolant pipe went down to around 60/65 Deg C as did the bottom of one side of the Rad but the Fan side(It's off-set) was about 45 Deg C at the bottom whilst the fan was on.

My system works perfectly and prevents the engine from overheating or running hot in stopped conditions.It was quite cool today over here e.g 15 Deg C.The fan rarely came on.I only noticed it when I was stuck in traffic.I'm running with a nearly full Rad at the moment and STILL my overflow bottle is not being used,which is what I would expect with a good,clean running cooling system.
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