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Discussion Starter #1
So I got an F3 a while back, been working on it here or there and it runs pretty well for the most part.. minus an intermittent lean condition that I cant figure out just yet. Anyways, Ive noticed that the bike will/can get up to operating temp at idle and fan will kick on at about 3/4 of the temp gauge so everything there is good..

So lets say I let the bike warm up to operating temperature at idle... I leave my place and shortly there after I can watch the temperature gauge plummet. Even the other day when it was near 70 degrees it will still drop to slightly above the line that is right above the C... when its colder (like tonight 55 degrees) the gauge will even be at the line almost.

Ive been around cars most of my life so I know some fluctuation in temp is normal but this seems rather drastic to me and I can say that except for in at a stoplight or at idle the bike NEVER reaches operating temp. Should I assume thermostat is stuck open, or maybe even removed or do these bikes not act like a car where it will be near operating temp at all times?
 

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Definitely something wrong. They should stay fairly static when moving (sounds odd lol). My bike sits at 80C even when it is cold out, maybe 78/79C if it is very chilly out, and maybe 82C if it is very hot out... all within about 4C of each-other despite external temps.

I would look into the thermostat as it sounds like it is likely the faulty part here. But she should stay constant (will always rise at redlights/not moving).
 

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Definitely something wrong. They should stay fairly static when moving (sounds odd lol). My bike sits at 80C even when it is cold out, maybe 78/79C if it is very chilly out, and maybe 82C if it is very hot out... all within about 4C of each-other despite external temps.

I would look into the thermostat as it sounds like it is likely the faulty part here. But she should stay constant (will always rise at redlights/not moving).
Thanks for the reply, thats kind of what my head was thinking anyways.. I just wanted another opinion on it.. thermostat on the way!
 

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You might have a giant air bubble trapped in there somewhere, can't hurt to try and bleed/burp the cooling system. Have you looked at the actual coolant and it's not old and nasty? If both of those are ok I would replace the thermostat regardless. Then if the problem still presents itself, have a look at the temperature sender and replace that also. G/L and let us know how you make out
 

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You might have a giant air bubble trapped in there somewhere, can't hurt to try and bleed/burp the cooling system. Have you looked at the actual coolant and it's not old and nasty? If both of those are ok I would replace the thermostat regardless. Then if the problem still presents itself, have a look at the temperature sender and replace that also. G/L and let us know how you make out
Coolant is vibrant green so im assuming all but brand new.. level is right up to the radiator cap and I was always under assumption that air bubbles would lead to a hot reading.. not an overly cold reading.
 

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I've noted a slight drop in temperature when running versus idle (eg traffic). It makes it easier to see because my bikes have digital thermometers. Ambient temp doesn't seem to affect this process much, but I have noted small temperature fluctuations between running conditions but not enough to concern me. If yours is concerning, there should be a way to test the circuit going to the temp-gauge with a multimeter.
 

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Definitely something wrong. They should stay fairly static when moving (sounds odd lol). My bike sits at 80C even when it is cold out, maybe 78/79C if it is very chilly out, and maybe 82C if it is very hot out... all within about 4C of each-other despite external temps.

I would look into the thermostat as it sounds like it is likely the faulty part here. But she should stay constant (will always rise at redlights/not moving).
He's in N.C. and not pretending to be British, so speak 'Merican, before I call Trump...:devil
 

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I only report in Celsius too...I have the slightest understanding of Fahrenheit. I think 0C was 32F and 100C was 212F - that's what I remember from maths class in school.

Doesn't usually bother me when people use different units - but it is irritating when people state measurements without units, as if we all use the same units worldwide or something...That 55 degrees outside could be 55C in Saudi Arabia! It could also be 55 frosted apples in cherry glaze syrup. Who knows.

Anyway, my 929 sits around 80C usually as well, but can creep up to about 105C if I've been stationary for a while.
As low as 59C if I'm moving in cool winds.

Reminds me of a story when some space exploration project to Mars in the last century was done by two teams (USA and Europe) they calculated thrust using different units. Yea...read the story.
 

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He's in N.C. and not pretending to be British, so speak 'Merican, before I call Trump...:devil
The 'ole girl has been set to C since I got her, so I learned what she sits at in C..... just easier to know what she is "supposed" to sit at when that's what you are used to looking at. Got fairly used to metric when I lived in Iceland.. just the normal system for them =)
 

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Discussion Starter #10 (Edited)
well I changed out the thermostat and the temp still wouldnt come up above 1/4 and it was over 70 degrees today.. I covered half the radiator (non-fan side) and boom temp held steady at half way... slight dip tonight when it was in the mid 60s.

on a side note, i have aftermarket fairings and the radiator is pure open...
 

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You might have a giant air bubble trapped in there somewhere, can't hurt to try and bleed/burp the cooling system. Have you looked at the actual coolant and it's not old and nasty? If both of those are ok I would replace the thermostat regardless. Then if the problem still presents itself, have a look at the temperature sender and replace that also. G/L and let us know how you make out
Grab an ohmmeter.
What for? when at idle or stopped in traffic the gauge will move normal up to operating temp, issue is when driving... temp plummets. After blocking half the radiator the past two days the temp has set at halfway at all times. Im just assuming to much air is hitting the radiator with the aftermarket fairings and keeping it to cool.
 

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What for? when at idle or stopped in traffic the gauge will move normal up to operating temp, issue is when driving... temp plummets. After blocking half the radiator the past two days the temp has set at halfway at all times. Im just assuming to much air is hitting the radiator with the aftermarket fairings and keeping it to cool.
I'm thinking the gauge is off. The radiator has a maximum efficiency and provided you have the OEM radiator, it's unlikely it's getting too cold unless you're riding in Siberian temperatures.
 

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What for? when at idle or stopped in traffic the gauge will move normal up to operating temp, issue is when driving... temp plummets. After blocking half the radiator the past two days the temp has set at halfway at all times. Im just assuming to much air is hitting the radiator with the aftermarket fairings and keeping it to cool.
When stopped, if you give it throttle and hold it steady, what does the temp gauge do? What happens when you let go and let it return it idle, does the temp gauge change at all? if you can post a vid, let the engine be at operating temp, film the tach and the temp gauge and bring the engine up to 3,000 to 4,000 RPM and hold it there for 5 seconds and then let go of the throttle. I want to see what the temp gauge does.

To much air doesn't make sense. When the engine gets hot, the thermostat opens up so the hot coolant can go through the radiator, the coolant in the radiator is already cooler than the engine, so it gets heated up and removes heat from the engine. When the engine gets back to the correct temp, the thermostat will close. The only way I could see an engine having too much cooling from the radiator is when the capacity of the radiator exceeds the engine by a huge margin and the ambient air is very cool. This would allow very cold coolant to reach the engine and take too much heat out of the engine. This is not the case that you have though, you don't have a giant radiator on your F3.
 

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Am I missing something? All of my CBR F2 or F3 always ran very cool. I've had about four or five of these bikes and I recall three of them running that way... That bike can stay idling for hours and never get hot... Even on 100 degree days, with my F3 track bike waiting to get on track while idling, I never worried about over heating.
 
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