what would happen if you just left the thermostat out of the bike ? run cooler ? i know it would take longer to warm up, but i wouldn't think anylonger than an air cooled one.

 

The way it is written, it sounds like the thermostat diverts the coolant to the radiators above 165*. I don't know it the hot coolant would flow thru the radiators without the thermostat. The hot coolant might just follow the path that the coolant takes before opening the thermostat.

I wonder if that was what happened here because the thermostat was defective:
https://www.hdforums.com/forum/new-r...ot-update.html

 

It could run hotter.....The thermostat can restrict the flow of water, slowing it down so it spends more time cooling in the radiators. You don't want the water to circulate too fast.

 

From the cooling system diagram, it appears that the coolant flows in 2 different paths. Which path the coolant follows seems to be controlled by the thermostat. It's as though the thermostat is a diverter. IIRC this would be different than the way a car cooling systems works. The coolant flow in a car is always the same path and the thermostat restricts the flow until a certain temp is reached.


AS Wharf Rat said sometimes the coolant flows to fast to be cooled without the restriction created by the thermostat. I've seen that occur in cars.

 

It won't run any cooler, just like a car, the thermostat opens at a minimum temperature, has nothing to do with controlling max temperature. Once it opens it stays open until the temp falls below that minimum temp. People think that if they put a lower temp thermostat it will lower the engine temp, doesn't work like that.

 

imo it would take too long to get to temp and may lead to carbon buildup.

 

i know it would slow the heating up of the engine with no effect on max temp. wonder if the ecm would cause problems ?

 

Without the thermostat the coolant could flow through the system to quickly, the coolant needs time to pick the heat up the heat in the heads and transfer to the radiators. The temp/degree of the thermostat is only for the minimum temp opening.

 

after reserching this it seems the ecm will read the differance between the engine temp and engine coolant temp. to big a differance and it will throw a check engine light with a code.