1971 BSA Thunderbolt. The engine is a 1971 Thunderbolt with 1971 Lightning Cylinder Heads (Twin Carbs). The frame is a 1971 Firebird Scrambler. The title states "Special Construction". I have known this bike since it was first sold by Dave Golden Motorcycles in San Francisco. The frame was swapped in 1975 due to damage. It has the original Union ignition key. This bike has all original British parts except for an updated battery. fuel petcocks (they don't leak) and repro K-71 tires. The bike has the original points and zener diode ignition system. The fuel tank and side panels were recently painted by Raber's in San Jose and the gas tank was tested and resealed at the same time. The carbs have been re-sleeved; the bike starts easily and idles smoothly. The original working Lucas turn signals will be included. I removed them because the bike looks better without them. The actual mileage is unknown. This bike is very reliable and fun to ride- I'm just getting too old for kick starters. The bike is located in Davis. Ca.