Quote:
Originally Posted by DannoXYZ
What you can also do is use lower-temp thermoswitch for fan so it comes on earlier. That way, up/down cycle is centred over lower mid-point temp.
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In theory.
In practice, you still have the same Qdot produced by the engine and the same Qdot removed by the radiator, so overall, you'll get a thermostat that opens earlier, causing slow warm ups, and then you'll reach the same operating temp once everything gets to equilibrium. Once you move to a low enough rated thermostat temp that the rated temp is below the natural equilibrium temp of your engine and radiator, it literally just sits open and does nothing. Thermostats will regulate an operating temp higher by going to a higher temp range, not lower by going to a lower temp range.
Ideally, a cooling system gets your engine evenly up to temp as quickly as possible, then maintains perfect operating temp for all duty cycles. Obviously this isn't possible with old school mechanical parts, but between a bypass, a proper thermostat temp, and carefully sized bypass flow to avoid temp oscillations and shock when the thermostat opens, one can get darn close. Conveniently, the thermobob makes this a solved problem.
TBH, no 250 should ever be overheating unless there's a problem. The radiator is very large, relatively speaking.
Quote:
Originally Posted by greg737
And...
Not to go off-topic or thread-jack but: The truth of the EX250 is that its cooling system design is from the Jurassic Era of motorcycle design and owners (of properly maintained EX250s) will tell you that their bikes are cold-blooded reptiles which rarely run at even half way up the temperature scale on the instrument panel (only climbing over half way when sitting in traffic).
I got tired of my EX250's cold blooded nature and I installed a ThermoBob unit on it. The ThermoBob is a cooling system upgrade which adds a feature that most, if not all, modern vehicles have these days. It adds in a small constant-flow bypass line that skips over the thermostat and radiator of the bike, plumbed into the return flow line post-radiator.
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BINGO! This right here. It legitimately makes a difference in how the engine operates in all temp ranges. It becomes problem free and does exactly what you expect it to do. No more cardboard needed on cool days.
The data speaks for itself:
https://shop.watt-man.com/Thermo-Bob...EARS-TB3-N.htm