Re: virago running on one cylinder

Wiring problems can certainly cause some of the problems you speak of. Broken or corroded wires and connectors are a problem on any older bike. Also, grounding is another problem with older bikes. Not to mention the various switches and relays. The best way to diagnois wiring problems is with a good wiring diagram and a voltmeter and some patience.
However, with the earlier Virago's that use the Hitachi carbs, many of the same problems are caused by poor carb adjustment, vacuum leaks and dirt or debris in the carbs. Hitachi's have to be squeaky clean and the pilot jet system is the biggest culprit since the passages are very small and difficult to clean properly. Backfiring through the carb or exhaust can be caused by running too lean or running too rich, so it is always a good move to check your carb adjustment first, particularily the pilot screw adjustment.

Thanks,
Bill