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Discussion Starter #1
I've been reading about the merits of installing a thermo bob. As I understand, one of it's main functions is to bypass coolant around the thermostat to pre-warm the coolant in the radiator, thus preventing the thermo shock of ice cold coolant rushing into already very hot water jackets in the cylinder when the thermostat opens.
My bike may be the exception, but doesn't the bike already bypass coolant when cold? I can start my bike from sitting overnight and within less than 60 seconds the radiator is getting hot. At 1 minute I cant hold the top of the radiator tank or it will begin to burn my hand. Meanwhile, the temp gauge hasn't yet started to move. This leads me to believe the stock KLR is already doing half the function of the thermo -bob. Am I wrong or is there something wrong with my new bike?
 

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The T Bob works to circulate coolant in the engine cylinder to maintain an evenly heated cylinder, then when the temp rises enough to open the thermostat, coolant flows to the radiator to remove the heat from the coolant. This action mimics car engine cooling systems, at least the older systems I'm familiar with.

I too notice that even with a T Bob, the radiator starts warming almost right away. I contribute this partly to the fact that there is a tiny bypass in the thermostat itself which allows some flow even when the stat is "closed".
 

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Discussion Starter #3
I think I was misunderstanding how the thermo bob worked. I went to Watt Man's site and read the pdf detailing how it works and have come to the conclusion that I need one of these and need one as soon as possible. Fall is coming soon and here in Michigan in stock form this bike will never heat up enough to keep the oil dry. Gotta love the aftermarket and deep thinkers that dream up this stuff. Great price too @ $125 shipped.
 

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I put the T Bob on about 3,000 miles ago. No cold weather riding yet, but cool nights.
I got the temp gauge overlay from him too and see temps stay pretty consistent 180-190 where before in cooler freeway riding it would drop pretty low on the gauge. Seems like a good thing to have.
 

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Installed the T-Bob last Monday. Running in upper 90's during the day and a low of 56°f this morning. Temp on gauge just rides aft of mid-level. Used to always run at the bottom of the gauge near the low mark.
 

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Thermobob??

I see where it can get the engine up to temp. quicker, but Just wondering, If you get stuck in traffic, does the TB keep the bike from over heating?
 

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I see where it can get the engine up to temp. quicker, but Just wondering, If you get stuck in traffic, does the TB keep the bike from over heating?
larry31,
It is and always has been the jobs of the Water pump, the Radiator, the Fan and/or Forward Motion to keep a liquid cooled engine from over-heating.

The Thermo-Bobs only 2 duties are to more Quickly bring the engine up to Proper operating temperature of 195-205 (middle of gauges) and help prevent it from dropping below that temp every time you achieve freeway speed.
 

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I wonder where the misconception came from that the T Bob helps anything run cooler? I’ve seen others online and here mentioning that.
If anything it makes it run warmer....that is, Making it warm up faster, and helping it not to dip down to lower scale of the temp gauge.
I’ve seen mine dip down well below 180 degrees in low 50’s riding even with it. Aluminum cylinder and block is a big heat sink after all.
 

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I wonder where the misconception came from that the T Bob helps anything run cooler? I’ve seen others online and here mentioning that.
If anything it makes it run warmer....that is, Making it warm up faster, and helping it not to dip down to lower scale of the temp gauge.
I’ve seen mine dip down well below 180 degrees in low 50’s riding even with it. Aluminum cylinder and block is a big heat sink after all.
The KLR650's have always struggled to maintain half-way on the gauge in the winter or cooler climates, because of the 160 thermostat.

The Thermo-Bob was originally designed during the Gen 1 days. With the smaller radiator the Gen 1 will generally operate at about 3/4 to 7/8th scale on the temp gauge in summer temps.
The Thermo-Bobs inventer / seller is from Phoenix AZ, so too many people just make the wrong assumption.

They never read ALL of the information on the sellers web-site. He does have information to help keep the Gen 1 KLR's below the 7/8th scale of the temp gauge, so they get easily confused as to the Thermo-Bobs true purpose.
 

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Discussion Starter #10
The KLR650's have always struggled to maintain half-way on the gauge in the winter or cooler climates, because of the 160 thermostat.

The Thermo-Bob was originally designed during the Gen 1 days. With the smaller radiator the Gen 1 will generally operate at about 3/4 to 7/8th scale on the temp gauge in summer temps.
The Thermo-Bobs inventer / seller is from Phoenix AZ, so too many people just make the wrong assumption.

They never read ALL of the information on the sellers web-site. He does have information to help keep the Gen 1 KLR's below the 7/8th scale of the temp gauge, so they get easily confused as to the Thermo-Bobs true purpose.
I confess to being one of those guys who had only read posts on the forum about it and not educating myself. For all KLR owners not currently running the bypass system I urge you to go to his website and download and read the pdf. it is very in depth in it's explanation of how it works. He tested it with thermocouplers and some fairly sophisticated monitoring equipment in various temps during real world riding conditions. What I got out of it is that it both quickly brings it up to a higher running temp and keeps it closer to a steadier temp than the stock form where the temp jumps up and down like a pogo stick. I have always been taught that oil likes to run hot to keep condensation boiled off and if you run short runs in spring or fall you'll see milky oil under the filler cap because the engine just doesn't get hot enough the way Kawasaki designed it.
 

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I confess to being one of those guys who had only read posts on the forum about it and not educating myself. For all KLR owners not currently running the bypass system I urge you to go to his website and download and read the pdf. it is very in depth in it's explanation of how it works. He tested it with thermocouplers and some fairly sophisticated monitoring equipment in various temps during real world riding conditions. What I got out of it is that it both quickly brings it up to a higher running temp and keeps it closer to a steadier temp than the stock form where the temp jumps up and down like a pogo stick. I have always been taught that oil likes to run hot to keep condensation boiled off and if you run short runs in spring or fall you'll see milky oil under the filler cap because the engine just doesn't get hot enough the way Kawasaki designed it.
Well, the INTERNET, clearly, has sold YOU, PaddyD!

Yet . . . qualifying, and quantifying, the MAINTENANCE IMPACT of the Thermo-Bob remains elusive (if not, eternally unattainable).

Hard to find any examples of component malfunctions traceable to the STOCK COOLING SYSTEM, run within safe limits. Hard to tell how many additional thousands of miles before major overhaul occur, courtesy of the Thermo-Bob.

The expected ravages of HEAT CYCLING and of THERMAL SHOCK are, well, SUBTLE in any visual appearance, or noticeable in terms of operational degradation.

No Thermo-Bob and your cylinder bore goes OVAL on you? Perhaps, but . . . hard to imagine how the relatively few degrees of temperature change applied to the cylinder causes such aberrations, given the EXTREME HEAT RANGE experienced in manufacture . . .

All this skepticism aside, the Thermo-Bob remains well-designed, competently manufactured, extensively tested, and responsibly marketed. All the benefits expected of the Thermo-Bob may indeed come forth. By all means, install one if you wish, and let us know the maintenance implications you experience. (How does that moisture get into the crankcase, milkying up the oil, during those short springtime runs?)

Like previous posters on this thread, I've wondered how some can believe a Thermo-Bob ENHANCES engine cooling. The vendor makes no such claim; some users do. Regardless, if the concept (Thermo-Bob enhances engine cooling) appears on the INTERNET, it MUST be true! :)

DISCLAIMER: My riding partner (85,000 miles on his '08 KLR650) LOVES his Thermo-Bob!
 

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Discussion Starter #12
Well, the INTERNET, clearly, has sold YOU, PaddyD!

Yet . . . qualifying, and quantifying, the MAINTENANCE IMPACT of the Thermo-Bob remains elusive (if not, eternally unattainable).

Hard to find any examples of component malfunctions traceable to the STOCK COOLING SYSTEM, run within safe limits. Hard to tell how many additional thousands of miles before major overhaul occur, courtesy of the Thermo-Bob.

The expected ravages of HEAT CYCLING and of THERMAL SHOCK are, well, SUBTLE in any visual appearance, or noticeable in terms of operational degradation.

No Thermo-Bob and your cylinder bore goes OVAL on you? Perhaps, but . . . hard to imagine how the relatively few degrees of temperature change applied to the cylinder causes such aberrations, given the EXTREME HEAT RANGE experienced in manufacture . . .

All this skepticism aside, the Thermo-Bob remains well-designed, competently manufactured, extensively tested, and responsibly marketed. All the benefits expected of the Thermo-Bob may indeed come forth. By all means, install one if you wish, and let us know the maintenance implications you experience. (How does that moisture get into the crankcase, milkying up the oil, during those short springtime runs?)

Like previous posters on this thread, I've wondered how some can believe a Thermo-Bob ENHANCES engine cooling. The vendor makes no such claim; some users do. Regardless, if the concept (Thermo-Bob enhances engine cooling) appears on the INTERNET, it MUST be true! :)

DISCLAIMER: My riding partner (85,000 miles on his '08 KLR650) LOVES his Thermo-Bob!

First let me state that I never ever thought it would let it run cooler. Actually, my goal has been and still is just the opposite. I want it to run hotter and at a more consistent temperature. To answer your question, (How does that moisture get into the crankcase, milkying up the oil, during those short springtime runs?) That moisture gets there through blowby and ordinary crankcase ventilation. When the engine oil is not allowed to consistently run at a temperature near the boiling point of water, (which in factory form it does not) in cold weather, it remains in the crankcase forming sludge. For winter riders here in the great north that water laden sludge can freeze restricting oil circulation upon startup. ( I have experienced this in an old shovel head Harley where the slushy oil froze in the oil lines) We all know how susceptible the cam journals are to oil starvation and how quickly it will trash the head. Consistent greater engine temperature is my goal and if I can achieve that for $125 I'm happy. If by chance all the claims of cylinder distortion by wildly fluctuating temps is in fact true and I also eliminate that at the same time then I'll be even happier...

Lastly, I did not need to be "sold by the internet" to know ANY engine will run happier slightly hotter than this one does. ANY time condensation is accumulating inside an engine to the point of it attempting to become an oil/H2O emulsification, it has been running too cool. I knew this bike was going to run cold the day I rode it out of the dealership in May when the temp gauge barely moved off the bottom of the scale.
 

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First let me state that I never ever thought it would let it run cooler. Actually, my goal has been and still is just the opposite. I want it to run hotter and at a more consistent temperature. To answer your question, (How does that moisture get into the crankcase, milkying up the oil, during those short springtime runs?) That moisture gets there through blowby and ordinary crankcase ventilation. When the engine oil is not allowed to consistently run at a temperature near the boiling point of water, (which in factory form it does not) in cold weather, it remains in the crankcase forming sludge. For winter riders here in the great north that water laden sludge can freeze restricting oil circulation upon startup. ( I have experienced this in an old shovel head Harley where the slushy oil froze in the oil lines) We all know how susceptible the cam journals are to oil starvation and how quickly it will trash the head. Consistent greater engine temperature is my goal and if I can achieve that for $125 I'm happy. If by chance all the claims of cylinder distortion by wildly fluctuating temps is in fact true and I also eliminate that at the same time then I'll be even happier...

Lastly, I did not need to be "sold by the internet" to know ANY engine will run happier slightly hotter than this one does. ANY time condensation is accumulating inside an engine to the point of it attempting to become an oil/H2O emulsification, it has been running too cool. I knew this bike was going to run cold the day I rode it out of the dealership in May when the temp gauge barely moved off the bottom of the scale.
Thanks for sharing your cold-weather small-engine operational experience, PaddyD! I have none . . . once snowmobiled in Labrador in December, but . . . had nothing to do with engine maintenance in that environment.

As to ANY engine running happier at a higher temperature than the stock KLR650 does . . . the MoPar engineers apparently disregarded the principle: My D2500 Diesel runs at 150 degrees Fahrenheit, summer and winter.

I never intended suggesting you thought Thermo-Bobs enhance cooling, PaddyD; rather, I cited the perceptions of others, as I think posters did on this thread.

If stock cooling system temperature fluctuations distort the cylinder bore, the phenomenon should be widespread, and I think occur early in the service life. Most Thermo-Bobs, from user reports, are installed after considerable mileage. Don't know the percentage of KLR650s running with Thermo-B0bs. Kawasaki's more highly-stressed Versys 650s have no radiator bypass systems stock; a market opportunity for Thermo-Bob.

Just wondering: Would a higher-temperature thermostat alone result in higher-temperature engine operational temperature?

Again, thanks for sharing your experience/observation regarding extreme cold weather small engine operation. Use your Thermo-Bob in good health!
 

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Interesting your Mopar runs so cool. Guess GM had the opposite idea. My 250 Express van typically would run 230-250 degrees. I replaced the fan clutch with a heavy duty to reduce that. Runs in the 190-210 range now even in extreme heat and AC running.
 

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Discussion Starter #15
Thanks for sharing your cold-weather small-engine operational experience, PaddyD! I have none . . . once snowmobiled in Labrador in December, but . . . had nothing to do with engine maintenance in that environment.

As to ANY engine running happier at a higher temperature than the stock KLR650 does . . . the MoPar engineers apparently disregarded the principle: My D2500 Diesel runs at 150 degrees Fahrenheit, summer and winter.

I never intended suggesting you thought Thermo-Bobs enhance cooling, PaddyD; rather, I cited the perceptions of others, as I think posters did on this thread.

If stock cooling system temperature fluctuations distort the cylinder bore, the phenomenon should be widespread, and I think occur early in the service life. Most Thermo-Bobs, from user reports, are installed after considerable mileage. Don't know the percentage of KLR650s running with Thermo-B0bs. Kawasaki's more highly-stressed Versys 650s have no radiator bypass systems stock; a market opportunity for Thermo-Bob.

Just wondering: Would a higher-temperature thermostat alone result in higher-temperature engine operational temperature?

Again, thanks for sharing your experience/observation regarding extreme cold weather small engine operation. Use your Thermo-Bob in good health!
Like I said, avoiding cylinder distortions that may or may not occur are not my main objective. As for simply using the 190 thermostat? Maybe, but I'm not an engineer so I won't give you a definitive answer to that, but my layman's perception is the bypass serves to keep the temp steadier by minimizing thermostat cycling as occurs without it.
As for my small engine knowledge? Small, medium or large, no engine likes to live on the cold side anymore than they like it on the too hot side of things. Extreme cold weather in an engine that runs overly cool on the warm days is not necessary to allow moisture to accumulate inside a crankcase. It happens anytime the oil doesn't get hot enough to evaporate or not hot enough for a duration of time long enough. According to the pdf on the website, in a stock KLR he had ridden something like 9 miles on the highway and the oil temp was only about 50 deg. Engines don't like oil running that cool for extended periods of time. That I believe is accepted by most all mechanically inclined people. Since it is an internal combustion engine and they all vent to the atmosphere, there will always be H2O in there regardless of engine temp. The difference is the accumulated amount in a cold running eng vs hot.
You do as you like and I'll do as I please..
 

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PaddyD, Are you familiar with my oil flow modifications for the KLR? They will increase the volume of oil to the Hot cylinder head, therefore heating the engine oil quicker & warmer. The 4 basic mods are quite simple to do.
 

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Discussion Starter #17
PaddyD, Are you familiar with my oil flow modifications for the KLR? They will increase the volume of oil to the Hot cylinder head, therefore heating the engine oil quicker & warmer. The 4 basic mods are quite simple to do.
No I can't say I have heard of your mods. What are they and how difficult are they to do? While I do have a decent grasp of the art of wrenching, I'm not a trained mechanic other than what I've picked up over the years. Also, will they affect my warranty? I have a 7 year bumper to bumper that I'd hate to void.
 

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Engines don't like oil running that cool for extended periods of time. That I believe is accepted by most all mechanically inclined people.
Except, perhaps, MoPar and Cummins Diesel engineers. No wonder these engines have such short service lives! :)

DISCLAIMER: The big boys on the playground say, 195 degrees F. is normal operating temperature for the 5.9 Liter Cummins Diesel; my thermostat may be stuck open, or . . . maybe I have no thermostat! (Truck's been like this since 2001.)
 

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A couple thoughts;

- hmmmm; my Cummin's (I have 4) run much warmer than that (195 - 215) and have 190 degree thermostats. After spending many years on the TDR, I'd suggest that common wisdom there recommends higher temps. . ......I even use a block heater most of the year since my commute is too short to get the engine/oil completely up to temp. I'm assuming you run an aftermarket temp gauge as the factory Mopar gauge is useless. Some reading on design temps; https://hspdiesel.com/dodge-5-9l-6-7l-cummins-low-temperature-thermostat

- the bore distortion on KLR's IS widespread.....it tends to manifest itself as severe oil burning and is more prevalent on early Gen2's due to the larger rad and poor ring design....perhaps you've heard of it? ;-)

- I agree that the distortion is likely to occur early on (how early, nobody knows) and it'd be best to install a Thermobob from new. Why install one after 5,000/10,000/20,000 miles? well because you can't go back in time and it can't hurt, only help.

- Watt-Man does make and recommend the Thermobob for the Versys (I had one of those too).


....at the end of the day, and as I've said before, there will never by any hard proof that your KLR lasted any certain amount longer with a thermobob but consider this: Bill now has 161,000 miles on his original, un-rebuilt 2004 KLR650 using nothing more than a thermobob and eaglemike's doohickey replacement. .....the proof is in the pudding for me.


Cheers,
Dave
 

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- the bore distortion on KLR's IS widespread.....it tends to manifest itself as severe oil burning and is more prevalent on early Gen2's due to the larger rad and poor ring design....perhaps you've heard of it? ;-)
I've heard of excessive oil use as a function of piston/ring design, 2008/2009 model years, but . . . not pandemic excessive oil consumption for Generation 1s or latter-day Generation 2s. If the bore distortion from lack of Thermo-Bob installation causes excessive oil consumption, looks like the phenomenon would be present continuously through KLR650 production history, 1987 (?) to the present. Would not ALL stock KLR650s, regardless of model year, appear vulnerable to the excessive oil consumption from cylinder distortion?
- I agree that the distortion is likely to occur early on (how early, nobody knows) and it'd be best to install a Thermobob from new. Why install one after 5,000/10,000/20,000 miles? well because you can't go back in time and it can't hurt, only help.

- Watt-Man does make and recommend the Thermobob for the Versys (I had one of those too).
Did you install a Thermo-Bob on your Versys?
....at the end of the day, and as I've said before, there will never by any hard proof that your KLR lasted any certain amount longer with a thermobob but consider this: Bill now has 161,000 miles on his original, un-rebuilt 2004 KLR650 using nothing more than a thermobob and eaglemike's doohickey replacement. .....the proof is in the pudding for me.
I congratulate Bill on his 161,000-mile longevity, and wish the same (and more) for you. The Thermo-Bob doubtless stabilizes coolant temperature more fully and at a higher nominal operating temperature than the stock cooling system. May these characteristics yield desirable maintenance consequences.

As to stock KLR650 cooling systems . . . is it possible Kawasaki designers and engineers specified inappropriate materials, clearances, operating design goals, etc., all dooming the machines to truncated service lives? Maybe so! :)

DISCLAIMER: The Physicians' Hippocratic Oath begins, "First, do no harm." The Thermo-Bob, to the best of my knowledge and belief, does no harm. Extended durability and reliability may follow all who install the product.

------------------------------------

Thanks for sharing your Cummins Diesel knowledge and experience; I've assumed my stock D2500 temperature gauge is accurate. Will try to run an independent, calibrated coolant temperature measurement.
 
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