Ok need help! Grandson has a 2009 KX250F dirtbike. It keeps dumping the coolent out the overflow. Have been told it was the radiator cap Replaced it with a new gage cap . Still builds up pressure and dumps the coolent. Then told the radiators must not be sealing where the cap sseal sits. Replaced the radiators with larger raceing ones. Did not fix the problem. Anyone out there have any Ideas? Or have had this happen to them. Thanks

 

It’s very possible that you have a blown head gasget. If the gasget is blown between the water jacket and the cylinder, compression will enter the cooling system and push the coolant out. Remove the spark plug and get an adapter to put compressed air into the cylinder an see if it blows out the coolant. If it does, it’s the gasget

 

thanks will chack that.