OK. Great that you don't think it has the problem. But I would check anyway. It is obvious form your description that something is wrong!

 

True. Ill check it. Ill do the pressure check as well..

 

At least if you check and it is not blown, we can think of another possibility.

 

Compression test first....... I am not completely convinced these are 'spin-free' motors.

 

The pistons should not hit the valves if the chain breaks on a magnum motor. Maybe when it happens at a high rpm the compression at that moment can bend valves or something, who knows. I'd do the tests these guys have suggested and go from there.