there must be something causing the starter motor to earth out.i would have said,poss side stand switch.i had a similar prob on my yamaha v max once.it kept spinning over but wouldn't start,i changed the side stand switch first,the cheapest option,then check the c.d.i pick up leads .bingo,high resistance,hugely different to factory spec,took a gamble on a second hand set of pick ups out of a low mileage bike being broken for spares,job done
