Why does Kawasaki put such a thermostat there instead of a 180? Does it save a few pennies? I'd imagine they'd cost the same. Is it an engineering mistake on their part?
I think you are missing how this works. First to @Steve in Sunny Fl
, what size is the rad hose going into the water pump and from the T stat? I see no reason why you couldn't use the T Bob for the Versys 650. My snow bike stat housing was experimental and I got one of the first castings, Bill installed a 10'F higher T stat in it as I wanted to use the discharge .The position of the thermostat was oriented in that #4 so that the bypass coolant was passing over the temperature bulb. I had two reasons, one , there is less room on the Mk-3 to mount the T Bob on the water pump / return side, and two, even though it is minor, you get stratification on the water pump side.
So a explanation I don't think I have ever done this way before. If you are old enough, in the 1960 to 1980's , it wasn't unusual to see cars or pickups with cardboard in front of the rad. Before I get too deep here, generally speaking , all cars have a coolant bypass, it is called the car heater, coolant goes from the water pump through the engine and bypasses the thermostat and radiator through the heater core and back to the return side of the water pump, as the coolant heats up above the setting of the T stat, fluid then starts to pass through the radiator, depending on how cold it is and how much energy you are putting into the motor, you may find that the returning coolant from the rad causes the T stat to close down, one way is to reduce the cooling effect of the radiator. This is a crude comparison because the T Bob is designed to maintain engine temperature, our car cooling system wasn't.
So in the 1960-1980 , T stats were cheap and cheaply made, you knew you had a T stat failed stuck open when after driving for half a hour you still didn't have enough heat to melt the frost on the windshield.So a interim measure was to stick some cheap cardboard in front of the rad. I use this to explain the OEM cooling system, during warm up, the water pump is dead heading, ( not 100 % true as a extremely small amount of coolant passes through the bleed hole, but compared to the T Bob, dead heading is appropriate because the fluid through the T Bob is about 20 times that of OEM during warm up).
I could compare the OEM cooling system to a coffee maker, a coffee maker heats water up within a chamber, when it is correct in is then allowed to pass through the coffee grounds / filter to the pot, during the heating process, the area closet to the heating element is the hottest, yes poor comparison, however my point is within the water chamber of our motor , there are going to be hot spots, the water eventually becomes one temperature, once it reaches the T Stat set temp and the stat starts to open, we get water flow to the rad, a equal amount of water comes from the rad to the water pump, this coolant is at whatever temperature the bike was stored in or ambient temp.Let me say it could be 10'C, when that 10'C fluid enters the pump, expect the thermostat to close down and that engine water chamber just received a shock / sudden temperature drop .
For those that understand and wish to correct me, the stat doesn't open 100 % instantly or close 100% instantly, it opens directly proportional to the temperature rise above set point, it also closes down the same way, however it does take time, so when this slug of cold coolant passes through the engine, it may be 5 seconds before it fully closes. Yes we just dropped the engine temperature in this process, eventually everything will warm up , close to operating temperature, but at or below 10'C your 650 Versys will never be at full operating temperature 100% of the time, even at 6000 RPM doing 130 KM/HR, my 2015 is at full operating temperature along with the oil, within 10 minutes of starting the motor and 100% of the time after that. One thing i missed stating, the engine is heating only the coolant within the motor and the bypass line, OEM the engine needs to heat all the coolant and depending on air flow and ambient temperature, the coolant entering the pump could be considerably cooler than optimum engine temperature.
The T Bob is a very clever design, it wasn't designed to make a car interior warm, it was designed to maintain a perfect operating temperature specifically for the benefit of the motor
. The secret is , and I am repeating myself,the bypass line only heats the coolant in the engine water chamber and the bypass line, as the coolant heats up to T stat opening set point, the stat slowly opens, initially a small amount of fluid goes through the rad, it returns through the T Bob, if that fluid were say 80'F cooler, it would first cause the stat to start closing however it is mixed with the hot bypass fluid, so what goes past the water pump is modified water temperature. In reality the T Bob was engineered to have the bypass line sized such that the engine never sees a change of more than 5'F , I am guessing at this, the open discussion by Bill has a graph showing this.
So you guys in Florida no worries, however , even at 60'F your 650 will not perform the same as my T Bob 650, when I am coasting or at low RPM's, the energy going into the motor is less, the flash Steve did has made a drastic change, at low RPM
( 2000RPM) my motor was always running hot when we had 90'F weather, not anymore.
Yes the motor in Florida without the T Bob may last just as long as my T Bob motor, and yes the T stat will close down as heat is removed by the rad and it will open up to increase flow to the rad when the engine temperature rises, and yes your engine is heating and cooling, expanding, condensation in the oil occurs and this action attributed to the elongation of the cylinders of the KLR where the T Bob was born. I said it about 8 years ago, the T Bob is a excellent investment if you ride in weather below 15'C.