Notice the K2 down front fender!
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Requires a lot of the expensive parts to do a restore to it. The single cab versions are not nearly as desireable as the hi-po models (Spitfire and Lightning), but a neat piece nevertheless.
And once you get it going - you'll have a new appreciation for the Hondas. I worked on Triumphs and Nortons at a dealership during the summers of 1970 and 1971 and you'll quickly learn why the Japanese invasion killed them off. But the nostalgia value alone is worth getting it.
We would have backward races with the Brit bikes. Put them on the centerstands and rev them up. They'd walk backward across a concrete floor.
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And you will also learn why Lucas is known as the Prince of Darkness.
I'd guess it is a Thunderbolt.
*EDIT* An you'll also get to know the Amal carb dearly. A company in California use to make intakes for the Brits to adapt Mikunis to them. Worked wonders for the the start, idle, throttle response.