Quote:
Originally Posted by Triple Jim
A Thermo-Bob may be nice, but it's not necessary to install that system just to keep the bike from overheating. I've run the stock system for several years since getting my '05 250 and have never had any cooling problems.
Let's see what Ponr says about the cooling system performance when he replaces the faulty thermostat.
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To be perfectly clear... I took pains to be very specific with my statements, I made it clear that I was broadening the topic in order to give a larger (and true) perspective/overview of the EX250 cooling system.
I thought my description of the situation was clear, I said, "... 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"
So I was not, in any way, saying that an EX250 owner would need install a ThermoBob in order to keep the bike from overheating.
The ThermoBob has the beneficial effect of: 1. it allows the engine to warm up more quickly, 2. it promotes and maintains a much more even thermal gradient across the entire water-jacketed cylinder liners and the cylinder head, 3. its constant flow of bypassed coolant promotes stability and more gentle temperature swings in the moments when the thermostat changes position (when the radiator flow of cooler water ramps up or ramps down).
Installing a ThermoBob along with a 195 degree thermostat will give the EX250 much better thermal characteristics across its operational envelope, from warm-up to stable cruising, and this combination
does not affect/will not reduce the maximum cooling ability of the bike's cooling system, because once engine temperature has reached 195 degrees the thermostat is 100% open so the engine temperature equation is reduced to just a heat-rejection factor of water pump output and total radiator surface area.
And, while running at any thermostat position less than full open, an engine temperature of around 195 degrees is a much more carb-friendly temperature for engine operation (than something around 175)