Head problem

[jdo4ex]

I have an 01 400ex w/ 440 big bore kit and the head will not stay tite. It's fine for the 1st few hours of riding then the head starts to seperate from the cylinder. 3 of the 4 head nuts come loose for some reason. the nut next to the timing chain never comes loose. Anyone have any suggestions?

[Choppers]

head stud starts to pull probably

[jdo4ex]

I replaced the studs, well 3 out of 4 anyway. I heli coiled those 3. Set the the correct stud height and everything. I've used locking washers and replaced the cap nuts. Even had the the head checked for warpage which it was and had it shaved. But all that was replace after I got my head back.