The number of times
I have had mails concerning the inability to remove a cylinder head
or the number of GS's I have seen with broken cooling fins where they
have been hammered...here's why.
When you remove
the head from a GS four, have taken out all obvious bolts / studs
and it still won't shift, before you reach for the club hammer look
here...
Click
for image --> 
The one you have
most likely missed (I did!) is an M6 bolt at the front of the engine,
between cylinders 2 and 3, UPSIDE DOWN...
