Yamaha200EK Electrical issue

[1985 200s]

Yamaha YTM200EK keeps blowing the head light bulbs. It comes on but when you get the rpm's up a little the bulb gets real bright then blows out. Also when the key is turned to light the engine shuts down. Only runs in on position. Light works in on position before it blows out. Don't have a battery in it now nor does it have a tail light. Any ideas? Thanks

[slothminx]

im not sure if it has anything to do with the battery not being there. but blowing bulbs is usually because the regulator that controls the voltage coming out of the lighting coil is kaput or not there. if you can get your hands on a multimeter you could measure what voltage your getting to the light. with the key thing i have heard before that its a position just for running the light and the engine isnt meant to run when its in that position so i wouldnt worry too much about that.

will

[slothminx]

just thinking about it the problem could be that there is too much juice going to the lamp as it has no battery to charge. i would get hold of a battery stick it in and see if the bulbs blow.

[Yamahauler]

The key thing is right, it will shut off if you put it in the 3rd key position. nothing unusual there.

[TeamGeek6]

Yes, regulator is either failed, has a loose connection or missing. Amazing what 30 volts will do to a 12 volt headlight!

Use an automotive headlight to test it so youre not exploding expensive motorcycle headlights.

If it were a battery system without a regulator, and the battery was missing, the DC voltage would drop and lights should go dim, so Im betting its an AC system (no battery).