A friend of mine brought his 1100RT to me with a similar problem. His neutral light would stay off, and he couldn't start his bike. If he put it in gear and held the clutch in it was ok. I was dreading having to get to the neutral switch, but a check of the wiring found a coupling plug on the left of the frame which had corroded. One of the 'spade' type connections had snapped inside the plastic so sometimes it would touch just enough to make a contact, others it wouldn't. 50p connector plug saw it fixed.