In the US they're called Nitro harleys but you would be hard pushed to find any Harley parts. Rules are basic, one engine, two cylinders, max capacity 3000cc or 2000cc supercharged. Standing start to 220mph in 6 and a bit seconds, possibly everyones favourite dragbike class, certainly mine.
Go and see them in the UK, Santa Pod Main Event and Euro Finals 2011, you wont be sorry. Motorcycle violence.