I have a Benelli Tornado TRE 900. On inspection I see the Water tank for the coolant is empty. I have tried to fill the tank from the coolant cap however no mixture seems to go into the tank. Infact, is just sits inside the coolant cap neck and then over spills. How do I go about topping the water tank up please?

Motorcycles - Benelli - Tornado Tre 900 - 2004 Benelli Tornado Tre 900