goes to goople
searches '1980 cx500 only runs on one cylinder'
comment from 2007: "replace this module right here:"
[broken Photobucket link]

edit: might as well add the problem. lol

if the carbs are clean and tuned well enough to be ruled out the problem is likely the CDI module as they are over 40 years old and are known to fail. if replacing the CDI doesn't seem to make a difference the problem is likely the ignition system on the whole. the next step in the process would be the stator but since you have to pull the motor to change it you may as well go ahead and rebuild the ignition system with modern components. there are a couple different aftermarket solutions such as Ignitech. i opted for Rae-San.