Here in Arizona all that's required to license an ATV is: a horn (bicycle or electric) rear view mirror, and a tail light/brake light mounted over your license plate. I couldn't find any wires coming from the ignition switch to operate my electric horn and brake light, so I connected them directly to my battery. Any standard brake light switch will work, just mount it using a nylon tiedown and keep the wires away from the exhaust system. I used one of those enduro tail/brake light black rubber things for my tail, brake light license plate mount which is wrapped around my grab bar. If you have any trouble finding any of these items, email me at nospammm@webtv.net I own an ATV dirt bike shop and we sell these items, we also have a service department who can install this system for around $200.00 (labor included) Check your local laws first though to make sure that its possible to license an ATV.

 

I may have your fix. have seen it twiceon two other 400ex's, both 99 and 00. with the bike turned off, replace the fuse. turn off your headlights. start the bike, then turn on the headlights, flick to high and low beam, if it pops in one or the other, is a break in the line at the back of your headlight reflector, the power line is grounding at that shroud. try disconnecting the headlight harness, and replace the fuse, ride it like you stole it. if it doesnt pop it again, you probably found it. make sure you wrap the wires good and use that braid thingy under the shroud to hold all your wires in place. pass this on, it has happened to 2 friends, but not on mine yet. all simptoms were the same as you described. good luck. TT

 

Ok guys now go to your local h-d dealer get a 30a breaker fuse to put in your 400ex fuse port I did it for my kid so he wouldnt get stranded when it pops let it cool down it will reconnect and your good it has worked on h-d for years and its done great for my kid just think out side the box guys!