Remove the thermostat and it will take a lot longer for the engine oil to get to running temperature. That can have an overall deterimental effect on long term engine performance. The cooling system is designed to operate in a specific range of temperatures controlled by the thermostat. If your engine is running hot and assuming the system is clean then the thermostat may be faulty. I was at Metric Motorsports in Lewisville yesterday dropping my Trophy off for some carb work when my son-in-law noticed a Triumph Street Triple on the shop lift. The mechanic showed us what was wrong with the bike, the cooling system was fully 100% blocked at the outlet of the pump. The owner had put some kind of additive in the coolant and it had turned to a gelatinous mass that hardened into a brick under temperature. The result was a blown head gasket as coolant steam pressure found the weak point in the system.
If you want some heat exchanger theory here you go: heat exchange rate is determined by three factors, the coolant mass flow rate, the specific heat capacity of the coolant, and the differential temperature between the heat source and the heat sink. Mass flow rate is a function of the pump and internal flow resistance in the system. We can disregard the Reynolds number for piping flow resistance here since we're onl;y concerned with the pump output and the thermostat's resistance to flow. When the engine is up to operating temperature the thermostat is maintaining a temperature band by modulating the flow through the radiator. The engine should operate in this band regardless of the outside air temperature (heat sink) as the thermostat and system design capacity is made to accomodate a very wide heat sink temperature band. So if you ride the bike in 20 degree F or 105 degrees F the engine temps are maintained around 190 degrees F. If you want a lower temperature in the engine get a colder rated thermostat. Removing the thermostat completely will provide max flow all the time so the bike will operate in a wide band of temperatures. At 20 degrees F it might be running at 90 degrees F and at 105 degrees F it might be running at 175 degrees F. (Examples only not a calculated value). With no thermostat the system flow rate doesn't change, specific heat capacity is determined by the coolant used, and the differential temperatures between source and sink will change, thus varying the operating temperatures.
Part of the reason for running the temps up toward 200 degrees F is to drive off any water in the oil which is detrimental to the engine internals. This moisture is first vaporized by temperature in the oil then routed through the crankcase ventilation system and out of the motor. Operating the motor at 90 degrees F will not drive that moisture out of the oil and you have water running around your engine's friction surfaces. Good luck with that.
One more note on coolants, there are a lot of snake oil sellers that will tell you they have an additive that can reduce engine temperatures. The best coolant is water and nothing but water, demineralized, degassified, water. The specific heat capacity of H2O is a LOT. It takes 1170 BTU's to turn one pound mass of water into one pound mass of steam (it only takes 1 BTU to raise 1 pound mass of water 1 degree F). Anything you add to water (like antifreeze) reduces its specific heat capacity. The engineers that design an engine and cooling system take the specific heat capacity of a 50/50 mix water and antifreeze into account when designing the cooling system to operate in a specific heat range under a wide variety of environmental conditions. If you want your cooling system to be the most efficient, make sure it's clean and has the proper coolant mix and the thermostat is operating in the proper range.
