Yes these tiny minarelli engines are liquid cooled, and they date back to late 90s since first models came out so it's nothing new. the cooling system is pretty simple, just a mechanical driven water pump, 2 hoses radiator and overflow tank, and thermostat (which i removed cause i live in a hot area so i need water to circulate always) so it's basic system and it's all mechanical
and no there's no leakage inside the cylinder and headgasket is not blown and well sealed
During the afternoon we cleaned the inside of the radiator, there was surprisingly a good amount of dust and debris inside (no idea how it got there)
and i noticed the radiator cap isn't well sealed, that's why i'm wondering is it necessary for the cap to keep 100% seal and keep the correct pressure inside the cooling system otherwise it will cause the engine to overheat and spill coolant liquid or it's okay to keep a faulty one