2000 Kx 80 Problems

Blown head gasket

yep

yep, its the head gasket

If it keeps doing it and the upper motor mount bolt seems too high to install the frame has stretched . While you are there with the gas tank off look at the junction of frame parts right at the syeering head/frame tube/motor mount spar junction for. cracks or peeling paint . Also check the small triangular factory gussets at the tubes that run into the center frame tube (the one that runs under the fuel tank )They crack if the kids is real big and fast or if hes a big jumper . The frames also chopper out when abused really badly or by adults bottoming really badly. The frame flexes and tries to pull the head off the cylinder .We had on that cracked the case at the swingarm pivot and pulled the studs out of the cyl head . Then again it might just be a bad gasket . But good luck .