I just bought a custom tri z with a stretched frame,3 over banshee swingarm and 8 over banshee axle.the bike is just so cool to ride and to look at.It has exhaust coming out of the radiator supply fitting on the top of the head.I put new hoses on it and new fluid change,I wanted all of the old antifreeze out so i kicked it over and it fired up and i saw some exhaust smoke out of the upper fitting,what would cause this

 

Welcome to the forums! A blown head gasket will cause this or a crack in the water jacket of the head. Do you have white smoke coming out of the exhaust pipe?