I just bought my first bike. A 1989 gs500. I am relatively mechanically inclined and so I bought it as a project bike but now I'm stuck. I have a strong spark in the left cylinder but not in the right. I replaced the ignition coil and the spark plug but still no spark. I tested both the new ignition coil and spark plug by hooking them up on the other cylinder and they work just fine. I then tested the wire leads for the right ignition coil and they are delivering the power specified in the manual. So I have power to and through the ignition coil but no spark. I did some research and it seems that my next 2 steps are the CDI and signal generator. Is there any way to test these so I don't have to replace both if I don't need to (they aren't cheap). Any help at all would be very much appreciated. Thanks!!

I believe the signal generator controls the coils, so if you have the specified power to them, it should not be that... But someone please jump in if I'm wrong on that.

- Bboy

I think there is a way to switch the wires coming from the signal generator to the CDI so that they would fire opposite of normal.  If you do that, and the other side's plug starts firing, then you know it's the signal generator. If the same plug still doesn't fire, then it's the CDI box.  Does that make sense?

I think I also saw somewhere else on this forum something about swinging a magnet over the signal generator to test this?  Maybe I'm dreaming...

Check the resistance in the signal generator coils, resistance info is in service manuals.  Easiest way to check a control module is to substitute a known good one and see if that works.

You might want to start HERE and work your way through the next several posts in that older thread.  The post I pointed at shows where the owner had tested his spark coils successfully, then moves step-by-step through the process of testing the signal generator coils.  (Apologies for the references to message threads that no longer exist.)  You may not need this level of detail, but it would save me from writing it all up again.  <grin>

And gsJack is right about the CDI; I'm not aware of any at-home tests you can perform on the unit.

Thanks everyone! Im gonna try testing both the signal generator and the cdi. I will update soon with my progress. Either I'll find the problem or shock myself pretty good. Either way I'm gonna learn something.