No, the condition of the reg/rec won't effect only one cylinder. It "simply" converts AC (generated by the flywheel) to DC, smooths the flow, and regulates the voltage to the electrical system to a more manageable 14.2V.
You want to be looking at the coils, plugs, plug caps, and slow running circuit in the carbs. If you still have no luck, and it all checks out, you could be looking deeper at the centre crank seal, or sticking piston rings.
First thing I would check would be the harness terminals on the coil. They tend to corrode/blacken, causing poor conductivity, especially if someone's been a bit over-enthusiastic in the past and rubbed the plating off the spade connectors with sandpaper!
_________________
Andy.
NSR-WORLD.COM
Please keep all responses to Forum posts on the Forum so that others may benefit.
Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.
Check us out on Facebook! Please "like" our page!