What You Always Wanted To Know About KLR650 Coolant Temperature (But Were Afraid To Ask!) - Page 2 - Kawasaki KLR 650 Forum
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post #11 of 21 Old 07-23-2019, 07:47 PM
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With the thermo-bob, not having the needle stuck to the low mark, takes the worry out of opening the throttle when I get on the highway in the morning. I also like the higher oil temperature during my winter commuting. And it makes me feel better about the 15,000 miles a year I put on my 2006 bike, data or not. That said, I just put an oversize front rotor on my wishlist.
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post #12 of 21 Old 07-23-2019, 08:50 PM
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I've found that where more than one engineering solution exists, the most complicated one is unlikely to be the best one in the long term and my coolant plumbing seems unnecessarily complicated by a carb' heat system which I can't imagine is necessary here in sunny Queensland and all those joins in short pieces of plastic pipe which are constantly degrading in our climate is a reliability concern. In addition I KNOW that there's a downside to too-cool engine temperatures although it's not as worrying as too-hot engine temperatures and my Kawasaki-provided guage clearly indicates my engine is spending a lot more time in the below-average temperature range than above-average (or even medium) range. Rather than add additional complication, expense and vulnerable joins to my system I'm inclined to just remove the whole carb' heat thing. Can anyone tell me with certainty whether simply removing and blocking off the two small fittings (one in the head and one on the coolant pump) is problematic for any reason? Someone has talked about the upper fitting coming off a small pump in the head but it just looks like a bleed hole to me and I'd like to block them both off rather than run a replacement line from top to bottom. This should have the side-effect of a small reduction in cooling system capacity since there's less liquid wandering around outside the engine.

The chart (above) clearly indicates that Kawasaki has provided a fan which acts to keep the engine temperature hovering around 200 F so that's probably the ideal range. I'm often lately thinking about growing up in a particularly frigid part of Canada where as winter approaches we'd generally squash a cardboard box flat and jam it in front of the car's radiator. In spring we'd simply throw that away and it meant the in-car heater actually had some hot liquid to keep us from freezing to death on long country drives. So I might experiment with a removable metal plate to cover the lower part of my KLR650 radiator. It seems to me this is a dramatically simpler and cheaper way of raising the operating temperature than installing yet more stuff (no disrespect to the purveyors of more technical solutions which seem to have the same goal). As always I'm happy to be persuaded differently by anyone more knowledgeable than me on this topic. Felix.

Last edited by Felix888; 07-23-2019 at 08:58 PM.
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post #13 of 21 Old 07-24-2019, 11:12 AM
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Felix,

1) I'd remove the carb preheat stuff too; whatever the rationale was for it, you don't need it - proven by several thousand KLR's in Canada and the northern US.

2) the thermbob's most important functions are to maintain coolant at a proper temperature and to drastically reduce the delta T between incoming and outgoing coolant (which cold shocks the cylinder). the fan helps the engine to not exceed the maximum temp but does nothing for cold shocking. Read the info and charts on Watt-Man's site for more info and I think you'll find that it's a far better solution than a pce of cardboard. Do you NEED one? ...see my previous responses.

http://watt-man.com/uploads/TB_Testing.pdf


cheers,
Dave
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post #14 of 21 Old 07-24-2019, 12:45 PM
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Felix888,
There is NO small pump in the head.
One can simply remove the spacer and install the thermostat into the head and use shorter bolts like most of the rest of the worlds KLRs. Then replace the water pump fitting with a pipe plug.

But,
Again I will suggest that you Take Advantage of the fitting at the cylinder head thermostat and the water pump cover to at least get your coolant up to the 70C of the stock oem thermostat Faster. Larger diameter fittings & hose would be beneficial, but even the tiny hose will help. This is exactly what the Thermo-Bob does, but it also includes two 90C thermostats.

Yes you can dispose of the actual carb crap.

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post #15 of 21 Old 07-25-2019, 02:22 PM
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Last edited by Tom Schmitz; 07-25-2019 at 02:27 PM.
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post #16 of 21 Old 07-25-2019, 09:09 PM
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Quote:
Originally Posted by Tom Schmitz View Post
Tom, you have obviously gone to the effort and expense of installing fiver transducers in various locations in your KLR's cooling system. The data is interesting, but it would be even more interesting if you would provide a BRIEF discussion of your findings and conclusions.

Thanks!

Jason
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post #17 of 21 Old 07-25-2019, 09:52 PM
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This past Sunday myself and 1 riding partner got a good ride in. We parted company about 30-40 miles from our respective homes and I needed to pick-up the pace due to lawn water tractor timing.

The earlier part of the ride, the Thermo-Bob 1 equipped '87 Gen 1 hovered at 7/16ths to 5/8ths temp gauge scale as normal for 85 - 95F temps. But on this one fairly deserted stretch of WY138, I pinned the throttle and held it, leaving an intersection. Up & over hill & dale so to speak for about 5 miles. Carrying 95 - 107 mph indicated at a digital max rpm of 7040. (6 psi camshaft oil pressure & forgot to look at the injured common tach, probably 8000+.) The temp gauge reached near 7/8th to the Red Zone but never touched it.

It would have been interesting to have had Toms oil temp sensor. My bike has been running the #44 / 2.18mm / .086inch crankshaft oil orifice for the past 4300+ miles.

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post #18 of 21 Old 07-25-2019, 10:25 PM
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@Norton 850,

Jason,

I have a K-type thermocouple in the head where the OEM sensor would go (Head), one in the lower radiator hose (Rad-Out), and one in the oil pressure test port (Oil). There's also a thermocouple up on the fairing which reads the air temperature (Amb).

These are all wired into a four-channel data logger and I am taking the data every five seconds.

What I am interested in is what I can do with the oil temperature. I'd like to see it come up a bit, preferably to 225F. So far my efforts have been a horrible and depressing failure. What I have done is fabricate some hard polyurethane foam insulators to wrap the sump. My hope was that I could bring the oil from ~200F to 225F. What I have seen, with not much testing under my belt, is that the increase in oil temperature could be explained away by the increase in ambient temperature.

What I am preliminarily led to suspect is that the KLR doesn't make enough horsepower to readily heat the oil to the temperature I want to see no matter what I do, absent high ambients (on the order of 100-115F). It doesn't mean that it's all hopeless, though, as my scheme may well work at lower ambient temperatures to keep the oil from dropping into the day-old-coffee realm. At lower temperatures, especially in the wet, I have seen oil temperatures drop to 150-160F. The greater Δt between the engine and the air may make the insulation idea effective. I might be happy with that if I could have 190F oil at 40-50F instead of lukewarm oil.

I have been working this project for about three months and haven't really accomplished diddly-shit. This is known as "Working at the speed of Tom". Projecting forward, I may have some idea what I am talking about in a year's time. It has been written up on my website as a read-along, but it's really nothing more than working notes.

That's the brief version. I didn't offer it up because it is really sorta off-topic. The cooling system data is a byproduct. I'm happy with the cooling system. Finally.

Tom [email protected]

The muzzle of the Luger looked like the mouth of the Second Street tunnel, but I didnt move. Not being bullet proof is an idea I had had to get used to. -Philip Marlowe

'Why' and 'How' are words so important they cannot be too often used. -Napoleon Bonaparte

Sting like a butterfly.
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Last edited by Tom Schmitz; 07-25-2019 at 10:31 PM. Reason: Kent speel gud
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post #19 of 21 Old 07-26-2019, 12:15 AM
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In case anyone's interested, I removed the excess carb' heat plumbing yesterday and stuck two 8 mm bolts into those holes. It's been suggested that this European / Aussie "bypass" reduces some of the cooling function, but my theory is that it's actually taking heat OUT of the cooling circuit (to pass on to the carb' and surrounding air). FWIW on yesterday's stop and go test run I saw the temp' needle HORIZONTAL for the first time ever I gather that's around the 90 C / 200 F mark but other factors may be at play too.

Today I jammed the probe of a digital thermometer into the collar of the upper hose where it joins the radiator - not quite head-exit-coolant-temp' measuring but pretty close. For sure, the engine runs colder than my other bikes have at speed (around 60 C) so a long period of standing idling allowed me to check for leaks and discover that the cooling fan pretty consistently kicks in when that indicates 93 C and stops at 87 C. I'm very happy with that as clearly Kawasaki has designed this to keep the "hot" running temperature hovering around 90 C or 200 F.

Decided that the bolts were ugly and bought a pair of black grub (set) screws, put a little plumber's tape around them and installed them instead - very hard to notice now that there's anything non-stock in that area. May take the head casting spacer off too and/or try a higher temp' thermostat one of these days but so far so good.
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post #20 of 21 Old 07-27-2019, 07:58 PM
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Quote:
Originally Posted by Tom Schmitz View Post
@Norton 850,

Jason,

I have a K-type thermocouple in the head where the OEM sensor would go (Head), one in the lower radiator hose (Rad-Out), and one in the oil pressure test port (Oil). There's also a thermocouple up on the fairing which reads the air temperature (Amb).

These are all wired into a four-channel data logger and I am taking the data every five seconds.

What I am interested in is what I can do with the oil temperature. I'd like to see it come up a bit, preferably to 225F. So far my efforts have been a horrible and depressing failure. What I have done is fabricate some hard polyurethane foam insulators to wrap the sump. My hope was that I could bring the oil from ~200F to 225F. What I have seen, with not much testing under my belt, is that the increase in oil temperature could be explained away by the increase in ambient temperature.

What I am preliminarily led to suspect is that the KLR doesn't make enough horsepower to readily heat the oil to the temperature I want to see no matter what I do, absent high ambients (on the order of 100-115F). It doesn't mean that it's all hopeless, though, as my scheme may well work at lower ambient temperatures to keep the oil from dropping into the day-old-coffee realm. At lower temperatures, especially in the wet, I have seen oil temperatures drop to 150-160F. The greater Δt between the engine and the air may make the insulation idea effective. I might be happy with that if I could have 190F oil at 40-50F instead of lukewarm oil.

I have been working this project for about three months and haven't really accomplished diddly-shit. This is known as "Working at the speed of Tom". Projecting forward, I may have some idea what I am talking about in a year's time. It has been written up on my website as a read-along, but it's really nothing more than working notes.

That's the brief version. I didn't offer it up because it is really sorta off-topic. The cooling system data is a byproduct. I'm happy with the cooling system. Finally.
Thank you for the discussion on the purpose of your transducers. I really think that if you're achieving an oil temperature of of 200F, you're good; no further work is necessary.

My car has an engine oil temperature read-out and when the engine is set to Normal Mode (EPA Mode) the engine oil temperature climbs to over 225F in 95F weather. If, however, I switch to "sport" mode, the oil temperature drops to about 205F. This is because in the EPA mode, the electronically controlled thermostat adjusts to achieve a higher temperature to help ensure a more thorough "burn" in order to reduce emissions. In sport mode, the EPA requirements are somehow bypassed and the thermostat is adjusted for the engine to run at at a cooler temperature, i.e. 205F versus 225F, in order to maximize performance.

So, the upshot based on the above empirical observations, is that 200-205F oil temperature is plenty warm enough for the oil to do its job while providing a denser intake charge for more efficient combustion.

Best,

Jason

Edit: Upon further thought, perhaps the "sport" mode anticipates higher RPM driving, which will increase oil temperature. So in an effort to maintain more consistent oil temperature, "sport" mode decreases the temperature in advance of higher RPM operation.

Also, I don't think lower oil temps will affect intake charge density, so there is no performance gain with lower oil temps as originally postulated.

Jason

Last edited by Norton 850; 07-28-2019 at 08:12 AM.
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