Radiator Question

[timex69]

Hello
how do you know when to stop filling your radiator..when it goes to the top of the tank or just covers the fins. I just bought a 2001 CR80 and i want to make sure i take good care of it.

[Red Rider]

Fill it to the bottom edge of the filler neck. After it is run for a while & heats up, the coolant will expand & completely fill the radiator, overflowing into the overflow bottle. This process purges the radiator of any air in the system. When the bike is shutdown & begins to cool, the coolant will shrink & suck coolant back into the radiator from the overflow bottle.

[MTS]

ohhhh so thats what the overflow tank is for...i never quite got what that did lol :D