freddy bosswell

HiIm a newby, i have the same prob with my xj 600n yamaha tried 2 tachos no luck, so i would try the igniter i think thats where the wire comes from. or it could b a bad earth i was going to run a earth wire from the battery to the tacho hope this makes sense!!! cheers freddy bosswell ps a month ago did not know what a xj yamie was hope i have not tread on any ones toes