Found what I was looking for. NAPA part #33488S 180 deg F/82Dec C thermostat, Stant #45868 (52 mm in diameter, one that came out 51.7 mm). One problem with it: it is too tall and the top cap will not sit flush with the bottom housing. One minute with the bench grinder to grind off the high spot on the thermostat and it fit fine. When grinding I did not go through the support, and I fully believe it will work acceptably. There also was a small brass plug on the NAPA?Stant unit that allows air to bleed out from under the thermostat but not water. The OEM Honda had a just a simple hole. I took out the brass plug on the NAPA unit thinking I wanted some flow through the thermostat when the bike was heating up so the heat from the engine would heat up the thermostat and allow it to open. I placed the hole on the opposite side of the two hoses from the engine so that as the small amount of coolant that passes through the hole has to flow past the thermostatic element on the valve so it will heat up and open when the coolant reaches the 180 degrees. The NAPA unit was $10 CAN, and probably could have gotten it for a better price elsewhere. Sorry Honda.