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Discussion Starter #1
I went out today for a ride. Temps were around 60F. I got the bike warmed up driving out of town. Once I got into the country doing 55mph the bike started cooling down. By the time I got back the temps were running right at the very bottom of the normal range (touching the cold range) on the gauge. Once I started riding around town again it went back into the normal range. I'm guessing this is a sticky thermostat. Where is a good source for purchasing such an item?
 

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I'm not sure that you have a problem here, the way you described the temp needle on the gauge sounds pretty normal. Regardless, is running "cold" really a problem? As long as both of your cylinders are firing right, I would think that running cold would improve engine performance. Now, if your fan is running constantly, I can see where that could be an issue.
 

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Old Twistie Sticks Rider
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I think if I did determine that I needed a new thermostat, I would just get one from the local Kaw. dealership rather than letting someone else decide which and whatever, after all its not gonna cost a fortune...
It does sound to me like it might be stuck open, as the air flow is having too much effect...
With my air cooled engine that would be how it is supposed to act, but I think with a radiator (best set up) I think you should be able to keep a more constant Temp. ...
Have a good one...Old Dog...
 

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In cold weather mine barely reaches the first hash mark. Very cold air going over the radiator is going to reduce coolant temperature more so than when the bike is stopped/traveling slowly. Sounds like your thermostat is operating normally.
 

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Old Twistie Sticks Rider
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In cold weather mine barely reaches the first hash mark. Very cold air going over the radiator is going to reduce coolant temperature more so than when the bike is stopped/traveling slowly. Sounds like your thermostat is operating normally.
That is true but with a properly operating and proper temp thermostat, I don't think that cold water should be flowing into the engine that cold, that is the thermostats job, to let water circulate at a temperature and to stop the circulation at another temp... I had a cage that the heater wouldn't work in cold weather, the mechanic put a hotter temp. thermostat in and it still didn't work, so he went to a still hotter one, and it still would not work, finally he put one in colder than the orig. and presto the water circulated and my heater worked fine... So it can go both ways...
PS-A wide range of operating temps will give you excessive engine wear, that is one of the advantages of water cooled over air cooled...IMO...
Have a good one...Old Dog...
 

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Agreed, OD, but once the coolant reaches minimum temperature, the thermostat opens. I'm assuming (and you know where that leads) that once the thermostat opens in cold weather, the cooling effect of the radiator keeps the coolant temperature just hot enough to keep the thermostat open. This is reflected in the minimal movement of the temperature gauge.
 

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It could also be that the thermostat is sticking open which would cause it to run cold. But at the same time it wouldn't allow it to heat up unless sitting idling for a time. I'd change out the thermostat just to be safe. That's what I would do but it's not my bike.
 

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Discussion Starter #8
Thanks. I'm a pretty good car wrench and if this were my car there would be no question it would require a thermostat change (probably wouldn't pass SMOG at that temp). I was just wondering if there is anything specific to motorcyles that would make it want to be cold. It doesn't sound like it.

I suspect I have the original coolant in the bike so I'm planning to change the coolant, the thermostat and the pressure cap at the same time to get ready for summer. We get triple digit temps in the summer so I'll need it up to snuff.

-Robert
 

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Here is an old thread with some automotive alternative suggestions for thermostats and rad caps on the vn7XX. Read the whole thread as some of the initial parts suggested are obviously the wrong size when compared visually, according to those posting in the thread.
http://www.vn750.com/forum/showthread.php?t=5207&highlight=accord+thermostat

A 160*F t-stat from a `79-`89 Honda Accord seems to fit and function OK after a year of riding. See last post by ktullu.
 
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