Cooling water flow control for a saddle-ridden type vehicle

A saddle-ridden type vehicle comprising:

• an engine;
• a water pump configured to supply cooling water for cooling the engine to the engine;
• a radiator configured to cool the cooling water having cooled the engine;
• and
• a cooling water flow control unit configured to switch a first circulation path of the cooling water, which is to be discharged from the water pump, to flow in the engine and to return to the water pump without flowing in the radiator, and a second circulation path of the cooling water, which is to be discharged from the water pump, to flow in the engine and to return to the water pump while at least a part of the cooling water flows in the radiator, in accordance with a temperature of the cooling water,
• wherein the cooling water flow control unit comprises a thermostat and a thermostat housing configured to accommodate therein the thermostat,
• wherein the thermostat housing is formed with a first passage into which the cooling water flowing out from the engine after cooling the engine is to be introduced and which is configured to deliver the introduced cooling water to the radiator, a second passage into which the cooling water flowing out from the radiator after being cooled by the radiator is to be introduced and which is configured to return the introduced cooling water to the water pump, and a bypass passage configured to communicate the first passage and the second passage each other, the first passage and the second passage being disposed to be adjacent to each other, and
• wherein the thermostat is configured to switch communication and cutoff of the second passage at a part of the second passage, which is positioned upstream of a connection part between the second passage and the bypass passage, in accordance with the temperature of the cooling water.