water somewhere its not meant to be. In your electrics or fuel.
Seart with checking for a spark. Take plug out and then put in the HT lead and rest end of plug on metal part of engine or frame. This will earth it. Start as normal and then with a mates help see if the plug is sparking as normal. Should be blue and bright. If no spark pop in a new plug to start with
Try this and then post back.
bb, January 2010