I have a 1971 Lightning that I bought in 1972. I rode it regularly through college until I graduated in 1980. Then I bought an XS 1100. I've kept the BSA with me, and have kept it in good running order. I've had all the typical Lucas electrical problems, and just deal with them as a matter of course.
I love this old bike; it's as close to a friend as a mechanical thing can be. I ride it in the Idaho sun on long two lane roads.
I had a '67 Thunderbolt 650. Bought it in barely running condition, tore it completely down, and built it up again with some help from Steve Wiley in Tangerine FL, and a few good friends. Kept it for a few years and sold it in '95. The most fun bike I ever owned; far from the fastest, but just pure motorcycling.
I put about 30,000 miles on it. Never left without a tool roll, and occasionally was glad I didn't. Switching from a monobloc to a concentric carb helped with the fuel problems. A Boyer solid state ignition went a long way with the electrics, and counter sinking all the screw holes slowed the oil leaks down.
Eye candy. Even better on the ears. Everywhere I went, someone would stop to talk with me about it. Good for some free beer at bike week too.
It was a torque monster on the low end, but hitting the ton was just plain scary.
I wish I never sold it. Helmets off to all you guys commenting here, we share something other bikers wouldn't understand!
Mine was a '69 Firebird Scrambler and my Heavenly Day, I wish I had never sold it. +1 on everything said above; low-end grunt and big-time vibration. British bikes have personalities like no others; there's a true communion between bike and rider.
My current Brit is a '69 Rocket 3, and she has all the same qualities as the twins, with a bit more poke and an exhaust note that rips the yellow line right off of the asphalt above 4500 RPM :-) And if you enjoy talking about your bike, an old BSA/Triumph/Norton etc. is the way to go. At the coffee shop of a summer Sunday afternoon, parked at the end of a long line of polished H-Ds and Japanese Death Missiles, the BSA attracts far more attention than anything else.
They say that if you smile every time you go into the garage, you've got the right bike! >Grin<