Hello all iv just had my dt125r rebored and rebuilt after around 15 minutes of steady riding i left it ticking over after a couple of minutes the engine stopped it has now lost all of its coolant out of the exhaust port the shop has told me that they will have it in to look at it but i would like some thoughts before i get there do you think its the head gasket although it was new or may be a warped head or could it be some thing else .

Hello all iv just had my dt125r rebored and rebuilt after around 15 minutes of steady riding i left it ticking over after a couple of minutes the engine stopped it has now lost all of its coolant out of the exhaust port the shop has told me that they will have it in to look at it but i would like some thoughts before i get there do you think its the head gasket although it was new or may be a warped head or could it be some thing else .

You know that it went out of this port?

The head gasket has probably gone but there could be several reasons why. It is also possible that the head is cracked and leaking water. When fitting a head gasket it is imperetive that the head bolts are tightened down correctly. It can also be useful to put some lubricant on the gasket so that it can move when tightening. You should also have checked the head for distortion, it must be flat.