Thermobob - Kawasaki KLR 650 Forum
1987 to 2007 Wrenching & Mods For maintaining, repair or modifications of Generation 1 KLR's. 2007 and earlier.

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post #1 of 30 Old 10-04-2019, 07:34 PM Thread Starter
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Thermobob

So What are the differences in thermo’s being sold? Watt man v Procycle
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post #2 of 30 Old 10-04-2019, 08:52 PM
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So What are the differences in thermo’s being sold? Watt man v Procycle
Good question!

Maybe, functionally, there are NO differences between radiator bypasses available.

Then . . . if considering a Thermo-Bob-like device, what are your own expectations? What consequences, pro and con, if any, do you expect from such a device?

I'll bet, at the operational level, either will stabilize coolant temperature more fully, and at a higher degree, than the OEM system. The actual "Thermo-Bob," as far as I know, has been designed and manufactured in the USA with transparency suggesting competent design and production, with extensive testing. Don't know much about the Procycle, other than the vendor seems an ethical business (from Internet reports). "Copy cat?" Generally, a device, "obvious to a journeyman craftsman skilled in the trade," (lots of radiator bypasses exist, over a wide range of liquid-cooled engines) cannot be protected by a patent [layman's (non-lawyers's) opinion].

Regardless, your own expectations and requirements remain key, IMHO.

“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; 10-04-2019 at 08:57 PM.
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post #3 of 30 Old 10-05-2019, 09:51 AM
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What is the thermostat temperature of the ProCycle radiator by-pass system?

The Thermo-Bob thermostat temperature is 195F, which is a Whole Lot better than the oem 160F for both engine cylinder & engine oil.

pdwestman
Modify at "YOUR OWN RISK"!

Still riding my 1987 KL650-A1. 85,000+ miles & counting
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post #4 of 30 Old 10-05-2019, 10:44 AM
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Originally Posted by pdwestman View Post
The Thermo-Bob thermostat temperature is 195F, which is a Whole Lot better than the oem 160F for both engine cylinder & engine oil.
Just askin': At what age and mileage did you install a Thermo-Bob on your 1987 KLR650?

("Inquiring minds want to know!")

“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 #5 of 30 Old 10-05-2019, 01:08 PM
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Originally Posted by Damocles View Post
Just askin': At what age and mileage did you install a Thermo-Bob on your 1987 KLR650?

("Inquiring minds want to know!")
Somewhere between 60,000 & 63,000 miles around about 2011-2012, IIRC.

pdwestman
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post #6 of 30 Old 10-05-2019, 03:02 PM Thread Starter
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It appears as though the only difference in Procycle version is upgraded silicone hoses. Everything else is the same
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post #7 of 30 Old 10-05-2019, 03:25 PM
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Originally Posted by pdwestman View Post
Somewhere between 60,000 & 63,000 miles around about 2011-2012, IIRC.
Thanks for sharing! Glad your engine endured those miles before the modification.

Back during the excessive-oil-consumption disaster of 2008-09 models, some opined the lack of a Thermo-Bob was responsible for this oil-guzzling phenomenon. Others insisted (and, probably still insist) the lack of a Thermo-Bob results in distorted (i.e., "ovalized") cylinder bore cross-sectioning. Don't know if those of this persuasion consider installation of a radiator bypass corrects this bore anomaly or not.

Regardless, the Thermo-Bob appears responsibly marketed, performing as advertised (stabilizing coolant temperature more fully and at a higher nominal operating temperature than the OEM cooling system), AFAIK. The 100,000-mile 2008 model of my riding partner proudly sports a Thermo-Bob!

“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 #8 of 30 Old 10-05-2019, 05:57 PM
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Quote:
Originally Posted by Damocles View Post
Thanks for sharing! Glad your engine endured those miles before the modification.

Back during the excessive-oil-consumption disaster of 2008-09 models, some opined the lack of a Thermo-Bob was responsible for this oil-guzzling phenomenon. Others insisted (and, probably still insist) the lack of a Thermo-Bob results in distorted (i.e., "ovalized") cylinder bore cross-sectioning. Don't know if those of this persuasion consider installation of a radiator bypass corrects this bore anomaly or not.

Regardless, the Thermo-Bob appears responsibly marketed, performing as advertised (stabilizing coolant temperature more fully and at a higher nominal operating temperature than the OEM cooling system), AFAIK. The 100,000-mile 2008 model of my riding partner proudly sports a Thermo-Bob!
Damocles, Yours is the First I've heard of anyone suggesting the addition of a Thermo-Bob would correct the so-called "ovalized" bore. Did you just make that up? Interesting thought non the less.

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post #9 of 30 Old 10-05-2019, 11:22 PM
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Damocles, Yours is the First I've heard of anyone suggesting the addition of a Thermo-Bob would correct the so-called "ovalized" bore. Did you just make that up? Interesting thought non the less.
In my post, I intended disclosing my own ignorance of whether the concept was harbored by anyone or not:

"Don't know if those of this persuasion [lack of a radiator bypass distorts a cylinder bore] consider installation of a radiator bypass corrects this bore anomaly or not." (Bracketed phrase added to quotation for clarification.)

Again, I apologize for my, "Failure to communicate!"

Does the lack of a Thermo-Bob distort engine cylinder bores? On ALL KLR650s running without radiator bypasses? If so, in the service life of KLR650s, early installation of Thermo-Bobs appear critical, if the ovalization is not corrected by the device.

If a radiator bypass only PREVENTS cylinder bore distortion, I'd wonder whether any non-Thermo-Bobbed engine has a symmetrical cylinder bore; if the bore geometry remains true without a bypass, I'd wonder why. Don't know if the vendor claims avoidance of cylinder bore distortion from use of the product, or offers any test data to that effect.

Just for the record, I think evidence suggests incorrect piston/ring design and/or construction was responsible for the excessive oil consumption of the circa 2008 model KLR650s, not the absence of Thermo-Bobs. What evidence? Fewer instances of excessive oil consumption reported after re-design of pistons and rings by Kawasaki, say, on circa 2009 and later models. My opinion only; YMMV!

Then again, some thought the absence of a PCV Valve Mod was the cause of excessive oil consumption!

“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 #10 of 30 Old 10-07-2019, 09:50 AM
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No adding a thermobob won't correct a pre-existing bore problem. Again, here's a related post on the subject;Honestly I think the bore has a propensity to go out of round on the bottom end regardless......but the T bob may lessen the distortion to the extent that the rings can compensate. Cary theorized that after a number of heat cycles the bore tends to become relatively static - which is why it stays fairly stable after a 685 rebore job. The '08's and '09's have a well deserved reputation for oil burning due to the ring (re)design, not because the bores are way worse than earlier or later bikes.....this is based on my review of some of KLRCary's material as well as my discussions with Eaglemike. Cary described the bore distortion as a design issue. Mike's belief is that if you put an earlier or later piston/ring set into a virgin 2008 or 2009 bore that it would have no greater chance of being an oil burner than other years.

To recap my thoughts;

- early Gen2's ring design was poor leading to a much higher incidence of oil consumption; as the bores distorted the rings couldn't control the oil.
- KLR650's have a propensity for some degree of bore distortion due to the design (lack of support on the bottom end of the sleeve and the thickness of the sleeve)
- the bore shape tends to stay relatively static after a certain number of heat cycles which is why the 685 kits usually solve oil consumption issues (and Mike's rings seal better)
- Aftermarket sleeves such as the 705 sleeve are beefier and don't distort much, if at all.
- the Thermobob helps lessen bore distortion by greatly reducing the delta T of entering and leaving water (cold shocking the cylinder). It's logical, given Cary's thoughts on the heat cycle issue, that the benefit of the thermobob is much greater if it's installed when new or very early in the engine's life. That said, it can only help regardless of when it's installed (do no harm! :-) )

....at least that's the synopsis I've come up with after some research and discussions with the guys that have the first hand knowledge and experience on the subject.


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