I have taken up a hobby of repairing and restoring older bikes. My current project is a 1986 VT500C. I detailed the bike and replaced rusted screws and bolts and just finished cleaning and lining the tank and cleaning the carbs. The bike starts and runs, but backfires when I rev it up and let off the gas and when driving, hesitates and loses power when accelerating at driving speed. The exhaust smells strongly of unburned fuel. I have the service manual and have gone thru most of the checks there, The ignition primary coils test out at 2.6 and 2.4 ohms, but are supposed to be at 2.0 Ohms and the secondaries test out within the specs. The pulse generators test out at 396 and 406 Ohms, outside of the 432-528 Ohm spec window. It has a weak spark at the two plugs I have checked. The Tachometer also goes on and off, which according to the manual, runs off of the CDI. I suspect it has a faulty Capacitor Discharge Ignition (CDI).I have only found one place that sells aftermarket CDI's. They want about $400 for one, which is about one third of the current value of the bike. I am almost considering doing this. Because there are no specs from Honda on how to test them, the only way to do so is to install it in another bike that is working and see if works. I am considering "surgery" on my CDI to check and replace any obviously bad components. I have replaced popped capacitors in other electronic before, but this might end up being more of an "autopsy". I could use any help you might be able to supply to get this old beauty back on the road and running strong.