Join Date: Mar 2009
Location: Clifton Beach, Tasmania, Australia
Unfortunately or fortunately as the case may be it is a well known problem and well documented. Many probable causes but in my case it was bad ignition switch contacts which had to filed rather than just cleaned and in another post higher than normal resistance on the clutch switch.
I ended up putting an auxilliary kill switch in the battery earth circuit, just in case, along with new battery and bigger leads, new starter relay, overhauled starter etc, but in the end a simple case of a bad connection.
Make sure your battery is in good condition as that can contribute or cause the problem as well.