Since I bought the bike (a 99 EGC) a little over a month ago I have been having a weird issue where the tach will jump around on me, other times it would cut out while riding, and a few times it refused to start. The problem was random and it was pretty damned hard to track down what was going on.

I thought that the problem was related to something loose because I though I noticed (correctly) that it would come and go with going over rough road. But once I saw that as a possibility I could not replicate it.

Another couple of times the bike refused to start, then after playing with stuff it would randomly work. The bike would also throw an engine code for the tach and starter relay. It didnt seem to make sense.

I was out running errands over the weekend and the bike displayed all 3 problem, not at the same time, but worse than I had seen it over the past month. Then on the highway at 70mph, I went to use the right turn signal and brushed the kill switch, I didnt flip it, but I just touched it briefly and the bike cut off and the tach jumped around at the same time. I pulled over at the next exit, and with the bike running at a stop, I lightly touched the kill switch again and the bike died. It was like a lightbulb went off in my head.

My guess was that the kill switch had a faulty connection in it, if it was a fraction of a second that it would disengage then the tach would jump, but if when I shut the bike off it was disengaged, then it would have trouble starting until I played with it. A quick search of the shop manual and $60 later I replaced the kill switch and so far (65 miles) all seems good.

I still have a slight stumble at low speed/low engine speed, it pops out of the intake, and my gas mileage which was fairly crappy 30-35mpg has not been measured since fixed the switch.

 

Good job in finding the issue. Money saved.