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Yes.
But it is not recommended to install them with out installing a proper water re-circulating bypass.

Normk might supply you a 195 thermostat and instructions on how to install a bypass the hard way/permanent way/scary way. For him it is easy-peasy, it scares the pea-outa' me.

I find it better for most people, including me to purchase the Thermo-Bob 2 from watt-man at Welcome . I recon one could purchase just a replacement T-Bob2 stat from watt-man?
 

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Discussion Starter #3
I must be missing something....why woulden't a stat change do the trick by itself? It works in tractors cars trucks etc. and my old jeep so it should work in a KLR.

I understand the thermo bob keeps the temp steady in the 210 range on most days so a 195 thermostat alone should be better than the stock one to bring the temps up. I have one of his gauge overlays and my bike is always running cold in the winter even in fla. so you guys up north even colder. I have used cardboard etc. to block off rads in cold weather even with a higher temp stat on sub zero days even on bikes...maybe i will try that on this bike.

Maybe someone who owns or works in a part store could do some research to find a car stat that is the same size with a higher temp. or has Watt.Man already done that?
 

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Drifter,
Click on the blue hi-lighted "Welcome", in the post above yours.
Read and study watt-mans temperature graphs.

I said, not recommended.
But I do know a High School small gas engines teacher who is doing as you wish to.
To each our own, sometimes.
 

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I said, not recommended.
"Not recommended," by whom?

How does a higher-temperature (195 degrees F.) thermostat in an otherwise stock (no radiator bypass) cooling system could cause any maintenance issues?

Thermodynamically, a very similar effect to blocking part of the radiator airflow (as with cardboard, etc.), I'd think.

A "hotter" thermostat won't stabilize coolant temperature like a ThermoBob, but . . . should raise nominal coolant temperature, seems to me.

I have a "Normk" model higher-temperature thermostat; may drop it in just to see what happens. Please warn me of any danger, describing the failure/malfunction mechanism. Thanks!

[Further thanks to Normk for obtaining the higher-temperature thermostats and allowing me to purchase one.]
 

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............Welcome . I recon one could purchase just a replacement T-Bob2 stat from watt-man?
Watt-man will sell you a 195 deg. F. t-stat and o-ring for the T-bob 2 which fits the stock t-stat housing. I bought one from him. Although, I had previously fabricated and installed a bypass for an application unrelated to temperature control, so mine is sort of a T-bob 1-1/2.
 

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"Not recommended," by whom?

I have a "Normk" model higher-temperature thermostat; may drop it in just to see what happens. Please warn me of any danger, describing the failure/malfunction mechanism. Thanks!

[Further thanks to Normk for obtaining the higher-temperature thermostats and allowing me to purchase one.]
#1,
By Bill, himself. By Normk. By me. Do as you wish!

#2,
Like I told the H.S. teacher, it may take a few 10's of Thousands of miles to 'see the difference'. Compared to a proper bypass system.
How long are you keeping yours?? Do as you wish.

#3,
Normk's source is the original North American Continent Source.
He passed the info to Watt-man. Who would have done it with the original size thermostat if he could have, at that time!!!!!
 

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Thanks for the answers, Paul; I appreciate your patience and civility!

Once more, I regard highly the competent design and manufacture of the Thermo-Bob, and its extensive testing program. Just wondered, short of a Thermo-Bob, what harm a higher-temperature thermostat would cause, and how.

Thanks again for your consideration.

My riding partner, with now 65,000 miles on his '08 KLR650, still loves his Thermo-Bob!
 

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Discussion Starter #9
GoMotor, do you have a gauge overlay if so what temps are you running on the road after the stat change and 1/2 bob job?

Damocles, let us know if you notice any temp change if you decide to switch the stat. Are you going to do it this weekend? :smile2:

Sounds like Normk has done the work and found one, anyone know what they came out of? Watt-Man might be getting more of my money...:character00201:

My riding a KLR tens of thousands of miles are long past besides i could not carry that much Rotella! :wink2:
 

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Won't be this weekend, Drifter; will see about raising the priority. Fully experimental; no known problems with the stock cooling system; hope the higher-temperature thermostat doesn't introduce any, whatever they may be.
 

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GoMotor, do you have a gauge overlay if so what temps are you running on the road after the stat change and 1/2 bob job?..................:
I don't have a gauge overlay, but I know that the center of the scale on my gen2 is 210 degrees F. and each quarter scale is 30 degrees F. So, 1/4 scale is 180 deg. and 3/4 scale is 240 deg.

Mine runs very steadily at about a needle width below center which I call around 200 degrees F. By needle width I mean the fat part of the needle is just below the center of the little screw on the dial. Once the conditions are hot enough and the load on the engine is heavy enough the thermostat will go wide open and the temperature will float with the conditions as you would expect, usually up to a needle width or so above center. Call it 230 degrees.

If either one of my gen2 KLRs goes above 3/4 scale I stop and look for a leak. On five occasions that I recall when that happened I found the leak and repaired it with JB Weld or fixed the loose hose and continued on with my trip.
 

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If someone wishes to do my bypass system, it's only about $30.00 for thermostat, elbows , fittings and hose.

Here's some info on my bypass design. IMO, it's simple as pie:

https://www.dropbox.com/sh/pwrq95427ptenur/AABiCBU5uMtpnilgMLael0I-a?dl=0
The plumbing system you have shown here is very similar to the one I used. I tapped into the head on top between the temperature sensor and the thermostat making it a little easier to manage the drill and tap swarf with a piece of cardboard through the t-stat opening and under the drilling location. I now think it might be possible to put a tee on the existing sensor opening and use it for both the bypass and the sensor. This would eliminate the need to drill and tap the head. I soldered a 1/4" barbed coupling on to the side of a 3/4" barbed coupling to make a tee for the pump inlet hose, but I like your tap into the pump housing better.

When I first made the bypass I was just doing it to get some hot water with the idea of passing it through the handle bars for free heat to the grips in winter.

I too think most folks would prefer to get the complete system for Watt-man.
 

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The KLR thermostat is 160 F but Sega scooters have a 160 F or 180 F thermostat. I had 195 F thermostats made in China to fit the stock KLR housing.

The problem I see with running higher than 160 F is concern regarding theromoshock to the system. One might note that all of the non-thermostat bypass systems in motorcycles use only 160 F.

Chrysler were one of the last auto manufacturers I know of who used a non-thermostat bypass cooling system. It was used in the Neon, 2.2 & 2.5 engines which were all notorious for head gasket failures. My hypothesis is that the rapid and significant change in temperatures when thermostat opened caused significant changes in the expansion rate of the head versus the block. This seems to match the head gasket problems which seemed to be from the head and block sliding over the head gasket rather than expanding and contracting together.

I have the same concern regarding the motorcycle engines. A bypass system simply recirculates coolant within the engine to maintain the engine at a uniform temperature which reduces issues such as the head gasket wiping issue, cylinder deformation due to the huge difference in temperature between bottom and top + increases the thermal mass involved in thermostat cycling.

A major problem with an non-bypass system is that the thermostat only reacts to the temperature of the coolant surrounding it. In the case of the KLR, 40 degrees is not an unusual temperature difference between the spark plug and thermostat....in what? 3 inches?

What happens is that the coolant pocket around the exhaust ports heats up more than other areas of the head and far more than lower down the cylinder. When the small pocket around the thermostat reaches 160 F, the thermostat swings close to wide open and a rapid loop or coolant cycle occurs, bringing cold coolant up from the bottom into the thermostat pocket. The thermostat slams shut and then the pocket begins heating again. One can match the cold air flow and engine load so as to see the temperature gauge swing wildly.

When there is a bypass passage/hose the coolant within the engine cycles through the passage/hose from the thermostat pocket to the water pump inlet and up through the engine. This constant mixing (keep in mind that the water pump pressure with the thermostat closed can be 65 PSI) maintains the coolant at a constant temperature which encourages more even engine temperatures.

Rather than heating only a small pocket quickly to thermostat opening temperature, the entire coolant volume within the engine must be heated and cooled in order to cycle the thermostat. As a result, the thermostat tends to simply open the amount which is required to maintain a constant balance of flow through the radiator and bypass to balance the cooling needed. The gauge sits in one spot unless other factors intervene.

Once the thermostat is open, the pressure in the engine drops to about the radiator cap level. Since the engine heat isn't changing wildly, the engine isn't in a state of dissimilar expansion and contraction so the head gasket isn't in so much danger.

This allows use of a higher thermostat which is why I chose the popular 195 F as the temperature. The difference in engine operation is well documented. The KLR engine is designed to operate at 250 F+ so clearances are better at higher temperatures.

I don't recommend simply installing a higher temperature thermostat as outlined.

The Thermobob2 is a kit using the smaller, stock sized thermostat. Bill sells thermostats separately as Thermobob3 so that's what I recommend. I didn't want to deal with sales or to cut in on Bill so connected him with the supplier.

If someone wishes to do my bypass system, it's only about $30.00 for thermostat, elbows , fittings and hose.

Here's some info on my bypass design. IMO, it's simple as pie:

https://www.dropbox.com/sh/pwrq95427ptenur/AABiCBU5uMtpnilgMLael0I-a?dl=0
Most eloquent and well-reasoned brief, Normk; thanks!

[BTW; no speeka dropbox; assume the info accessible from the link is the same you previously shared privately with me (I lack the confidence, or perhaps the courage, to tap into my cylinder head!).]

I've a couple of obstacles in the path of getting my mind entirely around your concepts, but this condition is a function of my own limitations, not yours!

For one thing, I wonder how a water pump reaches 65 psi without triggering radiator cap pressure relief (I think a bleed hole exists in the stock thermostat).

Since you mention the KLR650 engine is designed to operate at 250 degrees F. plus (i.e., presumably, materials and clearances chosen optimized for that operating temperature), I wonder why the Kawasaki engineers didn't manufacture the cooling system to achieve that parameter value.

Then . . . since the Thermo-Bob thermostat opens when adjacent coolant reaches 195 degrees F., the aftermarket thermostat would open also at that temperature. Damage mechanisms aren't immediately obvious between the two situations to me, although stock KLR650 head gasket failures may be more prevalent than I realize (not unlike the Chrysler Neon examples you cite). After the thermostat opens, engine cooling appears essentially unchanged, Thermo-Bob or not, to me.

The heat cycling, as you mention, is greater stock than with a radiator bypass; any consequent heat cycling maintenance issues appear hard to quantify. Your declaration that ALL non-bypass liquid-cooled motorcycle engines use 160 degree F. thermostats may corroborate the inference: "Thermal shock" considerations drive the operating temperature choice.

Again, thanks for sharing your rationale, why you recommend the stock 160 degree F. thermostat instead of a 195 degree F. aftermarket thermostat in a stock KLR650 cooling system.
 

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Discussion Starter #14
Intelligent and polite conservation! :smile2:

The thermal shock idea is a valid point and i can understand how that could cause problems. That being said from many...auto ,truck, and tractor stat changes through the years and boiling tests of new ones i have noticed they do not snap open or shut its a slower process, that combined with the bypass in the stat and heat transfer through the block itself allows warmer water to flow before and after it starts to open. I agree the various bypass systems seem to be a more stable option than the stock system with a 160 stat.or a 195.

I have had other water cooled bikes in the past that ran at higher temps and were more stable than a KLRs swings up and down. If the KLR was designed to run at 250 a 195 stat would seem to make more sense. After the stat opens the first time with a 195 the thermal shock would be less than a 160. These things seem to survive..with the 160 well enough so the way i see it a 195 would make it even better being water temp stability is the goal. So which is better thermal shocks with a 160 or with the 195?

It seems Kawasaki should have spent a little more time on design. Then again we keep buying them warts and all......:)
 

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I forgot to ask if you have thought about the Ozzie carb heater plumbing and why they may require that in their climate?
I was curious when I saw that coolant was piped to the carburetor on Australian models.

Some air planes I had were equipped to provide heated air to the carburetors to prevent icing in the throats of the carburetors. I wonder why my motorcycles don't ice when I ride them at altitudes higher than that at which the planes iced.
 

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Discussion Starter #17
It makes sense on a plane with a carb, back in the day some aircraft injected water into the cylinder maybe they still do for all i know. Doing it on a bike i have no idea. Them boys down under are a bit off anyhow their drains even spin backwards.
 

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The temperature at the bottom of the cylinder, according to Bill Watson's measurements and my rough attempts to confirm, are often very close to ambient so not unusual to see 60 F at the bottom and a bit over 160 F in the exhaust port area. That means that the cylinder is tapered fairly significantly under many operating conditions.
Just to clarify, Normk, are you saying the temperature of the coolant at the bottom of the cylinder may be 60 degrees F., while the temperature at the thermostat may approach 160 degrees F.? At nominal engine operating temperature? After circulation? For how long?

I would think the coolant would conduct heat more readily and uniformly throughout the cooling system, but accept your observations and measurements; again . . . standing corrected!
 

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Some ATV's will Ice their carbs during snowplowing / ice fishing season here in dry Wyoming. ie Normally low humidity level. 5300ft elevation.
 

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Did the planes ice in the intake or on the wings?

Back in the 1960's we used to see some carb venturi icing on cars while travelling on the highway in near freezing rain. I can recall pulling the air cleaner and looking into the throat of the carb to see a ring for hoar frost.

I would have thought that Oz would be lower on the list of countries expecting carb icing. :)




I was curious when I saw that coolant was piped to the carburetor on Australian models.

Some air planes I had were equipped to provide heated air to the carburetors to prevent icing in the throats of the carburetors. I wonder why my motorcycles don't ice when I ride them at altitudes higher than that at which the planes iced.
 
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