The carb does not attach to the head. I assume you mean the bracket from the head.
Theres a bolt in next to the fuel cap. Its a 5/16 thread. Head bolt out of another motor works well.
The bolt at the front is 1/4. Ive seen smaller screws with a nut, zip ties and wire. If this is not done up right and someone keeps using it the mount can break off the top of the tank. And also on the later ones it can break the plastic inlet manifold as well.
