There must something not touching inside the switch. Since it turned on before and now the bike turns the switch is designed to turn power off to light while cranking. So it has to be back in that switch. pull it apart again and make sure the tabs are all connecting. I remember having to take apart the switch on my old 1800 for a similar reason.
If all else fails, replace bulb!!!Done and done!
Its nice to get your bulb blown.