Motorcycle Repair: Yamaha Ignition Problems, yamaha virago, spark tester

Question
Chris, hey, got a problem. I have a 1983 Yamaha Virago 500XV. The problem is I have no fire to the plugs at all. I have replaced the pick up coil assy to no avail. The CDI has also been replaced. If I attach a spark tester to the coil, as I turn the key on I can see voltage entering the system, then it fades out entirely. I believe the CDI is bad and there are no test for it available according to Clymer. I have checked the coils..they check good. Any other ideas? Thanks. The CDI is a used unit and ma be bad...but what are the chances the ciols are bad. My friend is in the motorcycle repair business he says in 16 years hes only seen 5 coils die! What do u think? Thanks man!
Chris D.Lake City Fl.

Answer
Hi Chris.
 The first lesson that you are about to learn is to NEVER replace any components until you have checked them all out.

 Test the coils as per the specs and test proceedures in the repair manual.  My guess is that they are bad.  The bike is 21 years old, so the coils are likely to be bad.  CDI boxes are expensive and by replacing the one you had, you spent money that you likely did not need to spend.  CDI units almost never go bad.  Coils, on the other hand, can and do with a lot more frequency.

Good luck.
FALCON