Thanks Charles. What would be the reason that it won't go in far enough then?

Edit: I checked where the bolt is going in with a better torch and the bolt doesn't seem to actually go anywhere. I'll try and get some better quality pics, but my cameraphone isn't very good.

Edit2: I feel a right plonker. The end that bolted in near the sprocket had swung down behind the frame and I couldn't see it. Thanks guys.
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If I have to take the carbs off once...