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Change your thermostat........

Old 03-31-2017, 01:06 PM
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Change your thermostat........

That is my new warning.....it is a very overlooked part and will cause you much grief if it fails closed, like mine did.

Yes the thermostat isn't cheap but as there are getting on to 20yrs old now, it really is time.

I did try to pass the info along on another site but it just got twisted into I must have blown a CCT and have made stuff up to cover that fact.

Sorry but just not true, so what actually happened?

I did miss the clues, though at that time I was just using my bike to go to and from my cancer treatments, so I wasn't at 100%.

The clues you get when it fails in the closed posistion (at least on mine) was it acted like it was getting hot, my analog gauge went up to around 3\4, or high enough to get your attention, then it dropped back down to just below the first mark on the gauge..... that is your warning.
You have just puked all the coolant out of the thermostat housing and things are going down hill from there...

If you don't shut it off then, you are causing damage. I didn't shut it off..... The other bit that tells you something is up is that, again in my case, was 3-4 drops of coolant on my left boot.

Took me a bit to figure it all out, replaced the stat and coolant...the bike ran fine for 2-3 months....then I broke the cam chain on the rear cyl.
This happened because I had slightly gauled the cam journal in the head on the exhaust cam. Why the chain broke and not the cam is beyond me....but either one would have had the same outcome.....one blown engine.

Cooling system maintenance is very important and can cause a lot of damage if you just let it go...... Does that thermostat sound to expensive to replace now?
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Old 03-31-2017, 02:09 PM
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Read the thread on the other site. I'm still at a loss understanding the response.
Thanks for the heads up.
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Old 04-05-2017, 07:19 AM
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Oh my. So did you have another engine? How long ago did this happen?

This happened to me with an automobile engine(would be hard to detect on a bike I bet) But was easier to catch when inside a car. I could see and hear what was going on and pulled over. Upon removal, I found the pin head had worked all the way thru the disc, then the spring just slammed it shut.
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Old 04-05-2017, 10:03 AM
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This happened last year and I ended up with a new to me engine with 10k miles on it.

So the bike is back together and running stronger than ever
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Old 04-06-2017, 08:36 AM
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Originally Posted by 8541Hawk View Post
That is my new warning.....it is a very overlooked part and will cause you much grief if it fails closed, like mine did.

Yes the thermostat isn't cheap but as there are getting on to 20yrs old now, it really is time.

I did try to pass the info along on another site but it just got twisted into I must have blown a CCT and have made stuff up to cover that fact.

Sorry but just not true, so what actually happened?

I did miss the clues, though at that time I was just using my bike to go to and from my cancer treatments, so I wasn't at 100%.

The clues you get when it fails in the closed posistion (at least on mine) was it acted like it was getting hot, my analog gauge went up to around 3\4, or high enough to get your attention, then it dropped back down to just below the first mark on the gauge..... that is your warning.
You have just puked all the coolant out of the thermostat housing and things are going down hill from there...

If you don't shut it off then, you are causing damage. I didn't shut it off..... The other bit that tells you something is up is that, again in my case, was 3-4 drops of coolant on my left boot.

Took me a bit to figure it all out, replaced the stat and coolant...the bike ran fine for 2-3 months....then I broke the cam chain on the rear cyl.
This happened because I had slightly gauled the cam journal in the head on the exhaust cam. Why the chain broke and not the cam is beyond me....but either one would have had the same outcome.....one blown engine.

Cooling system maintenance is very important and can cause a lot of damage if you just let it go...... Does that thermostat sound to expensive to replace now?
Great remainder, that T stat and those small hoses just sit and hide out of sight until there is an issue.

Your spot on, consider it a preventive maint task .... All hoses and new T stat, also gets you a look at the inside of the St stat housing where if you have a corrosion issue, you'll see it there in the open.
If you have access to a bore scope, check the radiator header tanks as well.

DO you think a secondary temp sensor (and gauge) located in a different location then stock would have clued you in?
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Old 04-06-2017, 10:15 AM
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Originally Posted by E.Marquez View Post
DO you think a secondary temp sensor (and gauge) located in a different location then stock would have clued you in?

A temp sensor in the block itself would eliminate the issue but there is no place to mount one that I can see.
In the thermostat housing is about the only place to mount the sensor and usually it works just fine. Though it is one of the high points of the system and one of the first to get a steam pocket when things go bad.
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Old 04-11-2017, 04:55 PM
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Will the OEM temp sensor screw into the threaded hole at the front of the crankcase which serves as the drain hole for changing the coolant, and could the lead from it be connected in series with the temp sensor at the T-stat housing?
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Old 04-11-2017, 07:01 PM
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You might be able to plumb one in there..... though my lazy fix is to change the thermostat every 10 yrs
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Old 04-12-2017, 07:49 AM
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Originally Posted by 8541Hawk View Post
You might be able to plumb one in there..... though my lazy fix is to change the thermostat every 10 yrs
Id go as far as to say, maybe even sooner....

$31 for T stat and o ring is cheap insurance every few years, say every second coolant change or what every works for you in your maint schedule.

Id guess if a rider really does well in coolant system cleaning and changing coolant that T stat should live 10 years...
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Old 04-12-2017, 08:56 AM
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Yeah we probably hit both ends of the spectrum. 10yrs is about max and I said that just because I do keep up with the cooling system maintenance.

Every second coolant change might be a little too much but then better safe...

So I will revise my statement to say change it after 5yrs but before 10yrs depending on how often you service the system.

Remember to change the radiator cap while you are at it....
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Old 04-18-2017, 09:29 AM
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Just bought a 'stat for my VTR, at 22k miles, and 20 years old, who needs that gamble? Thanks for the good info..
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Old 04-25-2017, 11:09 AM
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maybe not to everybodies taste. but mine wount give me problems because i removed it, end of problems.
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