What You Always Wanted To Know About KLR650 Coolant Temperature (But Were Afraid To Ask!) - Kawasaki KLR 650 Forum
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post #1 of 20 Old 07-22-2019, 03:55 PM Thread Starter
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What You Always Wanted To Know About KLR650 Coolant Temperature (But Were Afraid To Ask!)

What You Always Wanted To Know About KLR650 Coolant Temperature (But Were Afraid To Ask!)

This thread's objective: A SEMINAR on KLR650 coolant temperature.

Invited: Impressions, observations, experiences, theories regarding KLR650 coolant temperature. Comments may be critical, cynical, irreverent, and even controversial--one rule, they must be CIVIL, devoid of ad hominem (i.e., personal) attacks on other inmates and their remarks. Disagreement welcomed, but . . . stick to the issues (extra credit for positions bolstered by facts, valid references, and/or direct experience evidence).

O.K. I'll launch the first treatise (or manifesto, if you prefer):

Recent posts have suggested cooling system problems, some real, and some perhaps imaginary. I propose a diagnosis and postulate a cure:

Diagnosis: Micro-reading the temperature gauge. The stock cooling system is designed to keep coolant temperature within safe limits (a RANGE of temperatures, not one specific temperature); a somewhat broad spectrum of temperature values. Referencing Goldilocks, coolant operating within those limits is, "Just Right," that is, within manufacturer's design goals. The absolute, optimal, precise coolant temperature isn't a realistic meaningful or significant parameter, IMHO, as long as the cooling system remains operational as designed.

Cure: Kawasaki could have installed "Idiot Lights," in contrast to temperature gauges, on KLR650s. I think the more highly-stressed Versys 650 has only an idiot light (and no radiator bypass). Some automobiles muddle through without temperature gauges, relying on warning lights to signal dire conditions. My approach: Absent idiot lights, if the temperature gauge needle stays shy of the far red zone, "Don't worry! Be happy!"

Then again, maybe the Kawasaki designers and engineers chose cooling system operating values comprising tragic flaws. There may be, "One Absolute True Coolant Operating Temperature," wherein operation outside this precise point indicated on the temperature gauge constitutes ENGINE ABUSE. Running at the Chosen Temperature adds tens of thousands of miles to the machine before major overhaul is necessary, and results in significant increases in power output and fuel economy.

DISCLAIMER: No data nor direct evidence corroborating opinion expressed above exists; OPINION only. YMMV! Conflicting opinion, data and evidence welcomed!

CAVEAT: No criticism of the competently designed, manufactured, and tested, responsibly marketed Thermo-Bob intended. My riding partner, at 95,000 miles (will hit 100,000 this summer) on his '08 KLR650, LOVES his! While the Thermo-Bob stabilizes engine temperature more fully and at a higher nominal operating temperature than the OEM (stock) KLR650 cooling system; the maintenance consequences of reducing the dread HEAT CYCLING and THERMAL SHOCK phenomena remain elusive and difficult to quantify.

Did Kawasaki's coolant system design goals irresponsibly disadvantage KLR650 owners, specifying operating parameters (e.g., thermostat opening temperatures, etc.), dooming engines to shorter-than-necessary service life and lower long-term performance? Or were these operating values, even within a relatively primitive cooling system design scheme, adequate for nominal service life applications?

The Thermo-Bob definitely enhances the KLR650 cooling system by "modernizing" its operation. Is the mod essential, or merely nice to have? Does ambient climate play a role in determining the Thermo-Bob's worth?

O.K., thread launched! Please share your own experiences and opinions regarding KLR650 cooling systems! No offense taken from any forthcoming comments!

“You better put down that gun. You got two ways to go, put it down or use it. Even if you tie me, you’re gonna be dead.” "John Russell" (Paul Newman), Hombre
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post #2 of 20 Old 07-22-2019, 07:22 PM
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I'll bump the thread and reserve comments for a while.

pdwestman
Modify at "YOUR OWN RISK"!

Still riding my 1987 KL650-A1. 85,000+ miles & counting
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post #3 of 20 Old 07-22-2019, 11:22 PM Thread Starter
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Originally Posted by pdwestman View Post
I'll bump the thread and reserve comments for a while.
I can hardly wait!

I jest. I look forward to your comments, as well as those of others, pdwestman!

“You better put down that gun. You got two ways to go, put it down or use it. Even if you tie me, you’re gonna be dead.” "John Russell" (Paul Newman), Hombre
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post #4 of 20 Old 07-23-2019, 07:42 AM
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I think this subject has been discussed so much that it's lost its luster, so to speak.

I will say that I'm amazed at the number of folks that are so concerned about the delta-T in their cooling system but are not the least bit concerned about braking performance improvements or even brake maintenance. Not long ago I asked about alternative brake disc suppliers and received very few responses. However, if I had asked about the performance of the "Bob", I believe I would have received gobs of responses.

Jason
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post #5 of 20 Old 07-23-2019, 07:52 AM Thread Starter
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Originally Posted by Norton 850 View Post
I think this subject has been discussed so much that it's lost its luster, so to speak.

I will say that I'm amazed at the number of folks that are so concerned about the delta-T in their cooling system but are not the least bit concerned about braking performance improvements or even brake maintenance. Not long ago I asked about alternative brake disc suppliers and received very few responses. However, if I had asked about the performance of the "Bob", I believe I would have received gobs of responses.

Jason
Think of the discussion if you had addressed OIL, Norton 850! Or, TIRES!

BTW, in no way did I mean to confine discussion to the Thermo-Bob! Rather, I hoped for overall consideration of the COOLANT TEMPERATURE in general. In fact, the, "Where Does Your Temperature Gauge Needle Sit?" thread inspired my effort.

Now . . . how did you know I plan a thread on brakes and braking? Dispelling myths? Invoking leverage and geometry? Mentioning brake modulation? Sharing friction formulae? Pointing out surface area isn't involved in calculating static force of friction?

I'd really like to see inmates' views on KLR650 coolant temperature generally (I've an anecdote or two about a manual fan switch (involves BURPING the radiator) I'll probably post later in the thread, fair warning! ).

“You better put down that gun. You got two ways to go, put it down or use it. Even if you tie me, you’re gonna be dead.” "John Russell" (Paul Newman), Hombre

Last edited by Damocles; 07-23-2019 at 08:59 AM.
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post #6 of 20 Old 07-23-2019, 09:51 AM
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This thread smells of more than a little pot stirring and I believe I've made my position clear in at least a dozen previous posts but for the sake of discussion, I'll do a BRIEF recap;

- there are no "tragic flaws" or "design goals irresponsibly disadvantage KLR650 owners". The system is adequate as originally designed for the purpose it was intended, the price point of the bike, and will provide ADEQUATE service for most KLR's and their owners during the period that Kawasaki is concerned about longevity.

- A coolant system bypass (such as the Thermobob) is a BETTER system and the proof and data is out there as well as the fact that the vast majority of water cooled engines employ such a system. Do you NEED such a system? No, not IMO. Is such a system BETTER and likely to increase engine longevity? Yes, I believe so......in fact, if you read and understand all the data, you can't come to any other logical conclusion.

Dave
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post #7 of 20 Old 07-23-2019, 09:53 AM
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Originally Posted by Norton 850 View Post
I think this subject has been discussed so much that it's lost its luster, so to speak.

I will say that I'm amazed at the number of folks that are so concerned about the delta-T in their cooling system but are not the least bit concerned about braking performance improvements or even brake maintenance. Not long ago I asked about alternative brake disc suppliers and received very few responses. However, if I had asked about the performance of the "Bob", I believe I would have received gobs of responses.

Jason
I agree; the two most important systems to upgrade on the KLR IMO are suspension and brakes......everything else pales in comparison when it comes to functional modifications.


Dave
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post #8 of 20 Old 07-23-2019, 01:53 PM Thread Starter
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Originally Posted by DPelletier View Post

- A coolant system bypass (such as the Thermobob) is a BETTER system and the proof and data is out there as well as the fact that the vast majority of water cooled engines employ such a system. Do you NEED such a system? No, not IMO. Is such a system BETTER and likely to increase engine longevity? Yes, I believe so......in fact, if you read and understand all the data, you can't come to any other logical conclusion.
Any quantifiable data on increased longevity, Dave?

Such data may exist, but . . . all I've seen is, "It stands to reason . . . " opinion.

And, maybe it does, "stand to reason." If that's "proof," so be it.

(Again, didn't mean for the thread to be a referendum on the Thermo-Bob; I considered, "coolant temperature," a broader topic.)

“You better put down that gun. You got two ways to go, put it down or use it. Even if you tie me, you’re gonna be dead.” "John Russell" (Paul Newman), Hombre
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post #9 of 20 Old 07-23-2019, 03:42 PM
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Originally Posted by Damocles View Post
Any quantifiable data on increased longevity, Dave?

Such data may exist, but . . . all I've seen is, "It stands to reason . . . " opinion.

And, maybe it does, "stand to reason." If that's "proof," so be it.

(Again, didn't mean for the thread to be a referendum on the Thermo-Bob; I considered, "coolant temperature," a broader topic.)
Nope, as I've said in the past, the data or proof that you seek doesn't exist.....in fact I don't think it could even be reasonably obtained.

The physics behind the principles involved are sound and unless you question the honesty of Bill's testing, the results are pretty clear IMO.....at least they are in recording the reduction of temperature swings, etc. etc. .....the extent of the impact of those changes are where there isn't and won't be, any hard data.

To put it another way, you can make a logical argument that the increased longevity by stabilizing coolant (and oil) temps isn't significant for most KLR owners.....but you can't logically argue that the improvement doesn't have a positive benefit. ... regardless of whether or not you can quantify the extent of it.

Cheers,
Dave
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post #10 of 20 Old 07-23-2019, 04:30 PM
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I'm working towards something else and gathered this today. Thought I'd throw it in where angels fear to tread.

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Last edited by Tom Schmitz; 07-23-2019 at 10:41 PM.
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