You will lose the benefit of having the engine operate at a consistent temperature. Engine temperature without a thermostat will vary depending on ambient air temperature and the loading conditions of the engine. Engine warm up after a cold start will be delayed somewhat. I would expect any "problems" from not having a thermostat would occur during cold weather operation more than during summer time operation. Thermostatic control of coolant flow has several myths that arise in popular culture. One myth being that a "cooler rated" thermostat will result in the engine automatically assuming the new lower OPENING TEMPERATURE as its OPERATING TEMPERATURE. The rating of the T-stat only governs the temp where the T-stat begins to open allowing coolant circulation through the radiator. And under ideal conditions, that rating may in fact be the temperature the engine will operate at. But higher ambient air temps, dirty radiator cooling fins obstructing air flow, anything blocking air flow through the radiator, a collapsed coolant hose, etc can and will result in the engine temperature rising higher than the opening temp rating of the thermostat. Operating without a thermostat during cold weather will cause a number of problems, the most insidious being degradation of the engine lube oil due to moisture in blow-by gases condensing into the oil and never being driven out again by the beneficial "normal operating temperature" being attained due to "over cooling" the engine.

Tomplum,I tested wires that go to the coil.Light lit up & I changed coil but still wouldn't fire on left..Asked repair folks & they said it sounds like bad ignition module,around $300.If I can get somebody to haul it in they will test it out.If I find out I need ignition module I can order it online for $100. Wayne

Too many new batteries are sick right out of the box. Always best to buy your wet cell batteries at a place where they will load test the old one to make sure it is bad and the NEW one before you take it home. Triple check the battery cable connection ESPECIALLY the ground cable to engine and/or frame. A poor B+ or ground connection will lose a lot of current and can eat a new battery or kill a perfectly good starter. Also, make sure the correct winter viscosity oil is in that Kwacker Twin. If it is really cold there, thick oil can slow the spin way down.

I'm with the OP on leaving sleeping dogs lay. On the other hand, if the failure of a component can lead to much more serious trouble, like timing belts in "non-clearance" automobile engines, then I'd probably replace the part in question. So the question you need to answer is: "Is this a clearance or a non-clearance engine?" My experience with plastic parts has been that the life seems most correlated with age and how much stress is in the design. For a camshaft gear, if the engine is stopped with a valve partially open, the gear will have the valve spring force on it continuously until it is started again. That suggests that it might be an bit of an advantage to make sure the engine is stopped on it's compression stroke. For some engines this is easy to determine, and others not. Multi-cyclinder configurations maybe not. My dad had a Lister diesel generator with twin cylinders. He spray painted a mark on the flywheel where both cylinders had both valves closed. His concern was rust in the cylinders during long periods of waiting for a power failure. Best luck, whatever path you choose, tom