Check a liquid-cooled motorcycle’s coolant level with the engine cold. Use level ground and the position specified in the handbook. Read the reservoir markings. Access and the topping-up procedure depend on the model.
Choose a fluid that meets the motorcycle manufacturer’s requirements. Premixed coolant and concentrate are different products: Motul Motocool Expert, for example, is used without adding water. A concentrate must be diluted according to its own instructions. The motorcycle manufacturer also sets the replacement interval.
Check compatibility before mixing different fluids. For example, Motorex advises against mixing M4.0 Ready to Use with other coolants to preserve its intended properties. Simply topping up does not resolve uncertainty about what is already in the system.
Never open the radiator cap with the engine hot. A noticeably falling level or an empty reservoir needs a workshop inspection: a serious leak may be responsible. Repeated topping-up is no substitute for finding the cause.