This problem I've been having with my engine missing a beat every now and again and behaving erratically hasn't gone away like I thought. The problem now only exists when the lights are on. So it is electrical. But why only when the lights are on? Could it be a connection shorting that is part of the lighting system? Here is a wiring diagram; http://server6.theimagehosting.com/image.php?img=Yamaha.SR250.jpg&album=25062&fullsize=1 Any ideas where to look to try and solve this one? Thanks, James.