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Discussion Starter #1
Just an observation - a positive one. :)

My old bike would warm up quickly, but would also get hot rather quickly. It was an inline 4 MaximX.

I was practicing MSF stuff in an empty parking lot yesterday for about 10 minutes, and noticed that my temperature gauge hadn't really moved. I was grateful because my old bike would get hot rather quickly doing that kind of stuff.

The only downside is that the bike seems to take forever to warm up in the morning compared to my old bike. Luckily, I can plan for this one and start the bike sooner. I thought this was interesting, because I would expect it to be the opposite since this bike has a smaller block, and more power/cc. Maybe the cooling system on the Ex500 is oversized.
 

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...or maybe the thermostat is stuck open.

If all is well in the thermostat department and the ambiant temp is low put a line of duct tape across the top of the rad. You want the temp guage about in the middle of it's sweep.
 

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Mine does not ever seem to warm up unless I sit at a traffic light and then it cools right back off again. Its been cold but the other day it was in the high 40s and it still barely warmed up. I am getting a fair amount of condensation in the oil window as well. This is the first bike I have owned that was overcooled. Usually they are under cooled like you say and run hot.

I suspect its the thermostat sticking open but then this problem seems common on the 500. I might have the dealership check the thermostat and replace under warranty but then it might not be that at all. I believe the roots of the 500 power plant used to be air cooled and it might just be way overcooled when you ride it in the winter. I have a sheet of black cardboard. I might tape it to the radiator and see if that helps. Seems like a ghetto solution though.

Its also possible that the temperature gauge is a bit flaky and the difference between cold and normal operating temperature is very slight and that doing nothing at all about the problem will not cause any concern. I did put my hand on the crank area of the engine case and it was warm to the touch but not hot. The cylinder head provided a nice OUCH!! So its not like its really running that cold. Of coarse the moisture in the oil is a tall tale sign that is not as hot as it should be.
 

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Do these engines have any tendency to keep air bubbles trapped in the head?

Some cars/vans do that if they're not drained/flushed right, or if someone opens the radiator cap instead of adding fluid via the coolant reservoir.
 

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There were a series of posts on this subject elsewhere in this forum...I don't remember where now. But the bottom line was that in cold weather the bike really does not come up to temperature quickly, if at all. I noticed this when I did a ride in the high 20s, and my gauge basically did not move. Several people suggested covering part of the rad with a piece of cardboard, or posterboard, which I tried...and it works like a charm. It slips easily between the protective grille and the rad itself. I use one that covers about 1/2 the rad when the temp is less than 50 degrees F, and another that covers about 3/4 of the rad when the temp is in the 20-40 range. Below that, I aint gonna be riding. At any rate, this works really well, and if you're temp gauge gets a little high all you need to do is pull the posterboard out at your next stop.
 

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Discussion Starter #6
bitzz said:
...or maybe the thermostat is stuck open.

If all is well in the thermostat department and the ambiant temp is low put a line of duct tape across the top of the rad. You want the temp guage about in the middle of it's sweep.
The thermostat is definitely not stuck open. I was just saying that our cooling system is well designed, as opposed to my previous bike. As long as my thermostat is in the OK region, I am not going to worry about it. Builders are usually conservative, so their OK is OK with me. :) That is a lot of OKs.
Point is, mine runs in the low OK region while the temperature is in the 30s. I am happy with that. I am also looking forward to this summer, because I believe the bike will run relatively cool. :)
 

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Really the thermostat should stay completely closed until the engine reaches operating temperature making use of cardboard in front of the radiator a mute point. Since placing a piece of cardboard in front of the radiator helps bring the bike up to full operating temperature I would say this is not happening. I think the stock thermostat is so conservative it either never completely closes or opens well before full operating temperature is reached. Its also possible that the thermostat is not in an ideal location and it gets hot before the rest of the motor actually does and opens prematurely. I have not checked the service manual but I imagine playing and swapping thermostats is not easy and frankly risky. Plus it opens up a big can of worms come summer time. So as much as I hate it placing a piece of cardboard in front of the radiator is the easiest solution. Maybe what we need is some kind of fancy custom made radiator cover that easily snaps into place. It will have a couple of sliding doors on it so you can adjust the airflow. Perhaps one of the Ninja 500 friendly aftermarket suppliers could cook something up?

BTW, the Ninja 250 has the same problem. Many people have tried to fix it over the years with mixed results and they say the best thing to do is just block the radiator.
 

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And to think that REAL expensive semi-trucks do the same thing: they just have fancier snap-on water-proof covers... some w/ zippers down the middle for adjustment.
 

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Yes gang...the ol' posterboard is the high tech solution to this issue. The other post I was referring to earlier was started by...none other than me because of condensation in the oil window after a cold ride. You can search for it under cold weather riding/oil temp. I have had no further problems with condensation since using the posterboard.
 

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Discussion Starter #10
On my old bike, you always had some coolant flow through a minimum flow line so that you would not cavitate the water pump. I imagine the ninja has something similar.
 

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No there is no coolant Bypass circut (whatever that is) just a small hole in the thermostat disc. More to let air out of the head than anythig .

FOG
 

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eh, cars have 'em. thought maybe the EX would too. i was just tossing it out there. seen them before on other water cooled small engines (ATVs and the like). they're usually next to the thermostat. obviously not in this case.
 

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I found a plastic "For Sale" sign in the garage and trimmed it to fit 3/4's of the radiator. For now I just taped it into place until I find the ideal size. When I do I will spray paint it black and then carefully place it between the radiator and the wire mesh grill in front of it. Looks like it will fit with ease if you are careful. Thats about as non Fred Sanford as you can get. I doubt it will not even be visible unless you are aware of it.

I would like to try it today but my street I live on is solid black ice and its 27F right now :(
 

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Right on longhaul747! We can now dub you an official Ninja scientist e-pluribus unum. Seriously, I think you will find that works fine. Let us know.
 
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