my son bought a kxf250 nice bike went to the local track after a while the bike cuts out really hard to start again . changed the plug went ok for another 2 hard days on the track .then cuts out again hard to start changed plug noticed the oil was brown in colour changed the oil started the bike within 2 mins oil brown again , the water pump seals was changed by the previous owner . it's not losing coolant he's been told it could be the head gasket as there's not much compression on the kick start any ideas guys cheers