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Discussion Starter #41
I took the advise from InvisiBill and placed a SPDT-switch (on-on switch) between the two sensors. Now I can play around with the coolant temperature and the oil temperature while driving :grin2:

I expected the coolant temperature to rise much quicker than the oil temperature. On my bike, the opposite turns out to be the case. Within 9-12 mile the oil temperature is up to its reasonable stable operating temperature of 194 dgrF (90 dgrC). The temperature of the coolant takes a lot longer (at least 20 miles) to reach the 176 dgrF (80 dgrC) that the thermostat is set on. Some 6000 miles ago I checked the thermostat in a pot of hot water. Perhaps it did get stuck in the open position during that time. I'll recheck it on a later time.

The oil pressure meter that I bought some time ago is now also placed on the dashboard. It was again a surprise to learn what the pressure does during heating up of the oil.
With a cold engine, the oil pressure goes straight up to the pressure that the relieve valve is set on, when I'm riding at 6000rpm. At my non calibrated air compressor I set the relieve valve at 80 PSI (5,5 Bar). At the non calibrated oil pressure meter it says 107 PSI (7,4 Bar) at that moment :surprise: Somewhere in a later stage I'll build a test setup to calibrate the oil pressur meter. For now I'll presume that the real pressure is somewhere in the middle...
When the oil heats up to 194 dgrF (90 dgrC), the oil pressure drops to 49 PSI (3,4 Bar) while still running at 6000rpm. I did expect a drop in pressure, but not that big.
According to the manual, the pressure is normal. The manual says that at 4000rpm the oil pressure should be between 31 PSI (2,2 Bar) and 49 PSI (3,4 Bar). For now I won't change anything on the bike. Maybe later I'll go play around with the extra oil pump that is laying around and perhaps the cylinder head >:)



It is not really part of this topic, but it is worth mentioning that synchronizing the carburetors made the bike a lot more smoooooooth :grin2: And again for a bargain because the tool was complexly made out of scrap 0:)



Two old main jets of a former bike (Suzuki DR800, that's a big thumper!!) even serve as inline dampers. I never thought of this (got the idea from someone in the Moto Guzzi Club Netherlands) but it works brilliant!

 

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I expected the coolant temperature to rise much quicker than the oil temperature. On my bike, the opposite turns out to be the case. Within 9-12 mile the oil temperature is up to its reasonable stable operating temperature of 194 dgrF (90 dgrC). The temperature of the coolant takes a lot longer (at least 20 miles) to reach the 176 dgrF (80 dgrC) that the thermostat is set on.
Search for Thermo-Bob info here. The stock cooling system is a single loop. While the thermostat is closed, the only flow in the system is through a ~1mm bypass hole. This keeps the warm coolant in the engine from flowing out to the thermostat, which keeps the thermostat from opening, which keeps the coolant from flowing, which... Since the temperature sender is in the thermostat housing, it's not accurately measuring the temperature of coolant in the engine, due to the lack of flow from the engine to the thermostat.

With a Thermo-Bob style bypass, the coolant is always flowing in a loop through the engine and thermostat housing, resulting in an even temperature. When the thermostat heats up and opens, it allows coolant to flow out to the radiator to get cooled. If it cools back down again, the radiator is cut off again. This gets the bike up to optimum operating temperature more quickly, with fewer temperature spikes, and allows you to pick a thermostat temp that matches desired engine temp.

Here are graphs of in and out coolant temps from the Thermo-Bob guy's KLR testing.



The 500's dual coolant output tubes and combo thermostat housing/filler neck make it a pain to add a bypass though. Someone here used a T-fitting on the sender port, and I'm (slowly) working on modifying a spare housing I have.
 

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Discussion Starter #43
After 4 years I discovered I dumb mistake on my part in my oil temperature setup. There was some malfunction in the circuit. After measuring everything, the problem was fixed but I also learned something new. The (SPDT ) on-on-switch is cross wired internally. I never thought of that, It wired it as if it was straight. So all the time that I thought that I was looking at the oil temperature, I was actually looking at the water temperature, and vise versa 😊

Now that that is corrected, I can correctly keep an eye on the oil temperature. Yes yes, I know everybody has an opinion on the usefulness of that 😉
 

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Funny this topic cropped up again, I distinctly remember it. It also introduced me to the thermo-bob concept, which I found interesting but never dwelled much on it. However, the thermo-bob came up again somewhere and I decided this time to actually make a bypass for my EX based on his theory. I now have much more mechanical skills and plenty of spare parts to play around with different concepts. I took an old thermostat housing which was filled with nasty deposits and drilled holes in several different spots to see which would be best for mounting an 1/8" NPT fitting to a 3/8" line before using a good housing for the final design. I then got an in-line temp sensor adapter for the lower radiator hose and all I needed to do to make it work with an 1/8" NPT is re-tap the existing metric hole which went better than you might think. Once I figure out which angle fitting is best, I'll be installing it. With the bypass flowing directly through the thermostat and the temp sensor, I should have a much more reactive system. It still won't be ideal though due to a poor design of the thermostat housing, which I hope to modify some time down the road with the help of a machinist friend.

More on to the original point of the topic, being able to see oil temp is certainly useful, especially if you can view coolant and oil temp together in real time. Once I have my custom thermo-bob style bypass system in place, I may install an oil temp sensor like you have @Rammelbak.
 
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