exhaust header bolts

[Fazer Jake]

after spraying them for a week one seemed to snap off at the bolt still  will i be ok leaving it? i cant feel any leaks as such

[Fazerider]

I had a stud shear off flush with the back of the nut, the rest of the stud was still there so I made up a double length nut, welding the two together, and then filed one end narrow enough to fit into the usefully wide hole on the header clamp. That way it could screw onto the remains of the stud.
Of course, if it is an accessible one and there's enough left of the stud to get a grip on you might replace it... but it's usually one of the inner ones.

[Captain Haddock]

As long as you disconnect the battery and the ignitor from the loom you should be able to put a nut over the stud and weld the two together without causing any problems, run the engine till hot or use a heatgun/blowtorch to get the aluminium hot and the stud should come out ok.