Tuesday, 24 September 2013

Exhaust Bolt Holes Dilemma

You might have seen earlier in the blog, that the PO of this bike had used 2 or 3 different types and lengths of bolts to secure the 4 - 1 exhaust.  It seems that the securing flanges on this exhaust are wider than the originals and in order to get a good fixing, some longer bolts and different numbers of washes were used.  This is what I found:
Securing flanges:

Also there was only one exhaust gasket which was located on the no.4 cylinder.

But I also found that when I took off the headers, although all the bolt holes had the same depth, some of the bolt holes would only allow a bolt to be screwed in 6 turns, whereas other holes allowed up to 14 turns.  So this was the first hole (6 turns only until it was tight):
 And this was another bolt hole that allowed 14 turns.  You can see the same bolt beds in a lot further:
So I was thinking (since the hole depths were the same) there must be something wrong with the threads.  I tried to tap it out.  It was very stiff and I only managed 3 or 4 turns and all this came out:
I don't want to continue this exercise for fear of damaging the bolt holes completely.  Should I keep tapping it in?   


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