In a low tech engine like a merc 25 2-stroke. I spoke to a mechanic today who said 'we just remove the stock 120 degree mercury thermostat on the mercury 2-strokes'. I asked why, he stated it was less of a part to break, get clogged, etc. I understand that the thermostat straps the initial water volume so the block can heat UP to the proper temperature (which some people complain about [the water dribbling and not pissing fully] and some people mistake for a broken thermostat when they dont see the tell tale peeing hard enough). I did some reading. And the census is that in the older 2-strokes it can 'be ok to do in tropical climates'. But 'the manufacturer put it there for a reason' so I'll stick with it. Seems a cooler running engine can build up carbon faster and foul- but the older 2-stroke are rich engines to begin with so that's kinda moot there too. The block can also not heat up properly causing uneven piston wear, but the tolerances in a 2-stroke are also loose- so again - not a huge factor.