Big Duke 6
It does sound like the regulator/rectifier is kaput. You'll find it attached to the frame just beneath the clip which holds the forward edge of the fuel tank down. Remove the black plastic cover under this clip, and the regulator is just there - it's fastened to the frame with two bolts.
Replacing it is easy (if you buy an Electrex replacement, you'll find simple printed instructions in the box). It's a half-hour job at most. (..and it'll cost you approx. £70).
ps. I'm surprised you didn't get warning of this being about to happen. Usually, the red 'generator' light on the dash flickers as the revs drop.
14-Dec-2006, 14:20 
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