This MRB made stainless steel stud is an M7 to M8 repair stud for cylinders with oval exhaust ports if the threads have gone. 
 
  Drill the hole to 6.9mm then tap out to 8 x 1.25mm, then loctite the stud in place, a simple way to repair a cylinder. 
 
 
Product code: LUMBP0429