If you're going to continue riding in the cold, look into the Thermo-Bob.
https://watt-man.com/new-shop/thermo...l-model-years/
The stock cooling system is a single loop. Flow is determined almost entirely by whether or not the thermostat is open. When it's closed, the only flow is through the tiny 1mm bleed hole in the stat. For the most part, coolant sits in the engine getting hotter, and in the radiator getting colder. When enough warm coolant trickles through the bypass hole that some heat actually gets to the thermostat, it opens up and there's a surge of coolant movement. The hot coolant in the engine is replaced with the supercooled radiator coolant. It's even possible for coolant to make it all the way through the engine and back to the stat while being cold enough to cause the stat to close again, repeating the cycle. Also note that the temperature sensor is in the remote thermostat housing, so it's not directly measuring the temperature of the coolant inside the engine.
With a Thermo-Bob, the coolant is constantly pumped through the engine, past the thermostat, through the bypass line, and back into the engine. That whole loop should uniformly get up to the thermostat temp pretty quickly, regardless of ambient temp. Once it hits the stat temp, the stat opens and coolant is allowed to flow through the radiator to cool off, just as the stock setup does.
https://www.ninjette.org/forums/showthread.php?t=88799 has quite a bit of info on it, though most of the pic links are now broken.
Here's the report from a DIY bypass on an EX500 (the 500's cooling setup can't really accept a Thermo-Bob):
Quote:
I haven't had temperatures very close to freezing (or below) to get a full test in, however, I have ridden the bike in dry conditions around 40 deg F. The temperature of the bike during these conditions, across all speeds, is much more stable. Previously, the bike showed very wild fluctuations in indicated coolant temperature depending on the speed. Now the temps are very stable. While moving at nearly any speed, the needle sits just about the midpoint of the temp gauge. When stopped, it starts to creep up a bit, but never drops lower than that steady place on the gauge once I start moving, all the way up to 80 MPH.
Additionally, I can say more definitively now that the improvement in low-RPM performance seems very real. Previously, asking for any significant power lower than 3k RPM was pretty useless due to "lugging". Now, the bike will happily provide usable torque much lower in the RPMs, down to approximately 2.2K. It isn't a LOT of power, but its at least nicer than before. Idle also seems to be ~150 RPM higher. I don't have a clue what mechanism is at work to improve the low-end performance, but I like it!
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