Thanks for the replies.. I cleaned up the earth connections and then tried the engine again. It runs ok but when i rev it up to 6000 it becomes rough and the neutral light dims and flashes. I unplugged the rectifier and the engine reacts in exactly the same way with it plugged in or not. Does this mean it is not the rectifier causing the problem? Any ideas what else could cause this? I haven't tried riding it again.

I've ordered a new regulator anyway but probably won't receive it for a few weeks as the postal service here is pretty slack..

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