pas le temps de traduire le manuel du mécano. Mais ça peut être utile.
Engine cooling
Filling the system with coolant. Bleeding air from the system.
Check the coolant level when the engine is cold by following these steps:
-> Place the vehicle on the centre stand.
-> Remove the expansion tank cap and top up if the liquid in the tank is below the min. level rim.
-> The coolant consists of a 50-percent mixture of distilled water and an antifreeze solution with a base of ethylene glycol and corrosion inhibitors. Total coolant capacity: 1.2 I
-> Start the engine and rev it up a few times until the coolant reaches the working temperature of 60-70° C.
-> Stop the engine and, after a few minutes, remove the expansion tank cap and check the level of the coolant.
-> Top up if necessary.
Warning - To prevent the coolant from flowing out of the expansion tank while riding, never pour in coolant above the MAX level mark.
-> To drain the coolant from the circuit, loosen the drain screw shown in the figure, attach a rubber pipe to the hole and put the other end of the pipe in a container.

Pour la dernière phrase (purge complète du circuit) voici la vis en question :