its called a shear bolt and its to stop people tampering with them,i use a centre punch and put a dent in one of the outer edges of the top of it and then drift it round anti clockwise with a hammer and it will undo,obviously dont put it back on again use a new 6mm bolt of some description like an allen bolt.they also put a similar thing on the ignition switches to stop people tampering but they use a shear nut instead on a stud.
adam bike doctor
May 2010
howtomendit.com for free repair help, information and advice.
