This one puzzles me. A new 2000 LT160, running a few hours at night with the headlight fine. After a half hour break, jump on it to go again, and both high and low beam filaments are burned out in the headlight, I mean not even a flash as some headlights do sometimes. I replaced the bulb and away we went. Both High and Low beam working O.K. Then the same thing happens. Pull into camp with the headlight working fine. About an hour rest this time, jump on it, and the low beam filament is burned out. Again, when I started the bike, then turned on the headlight (the switch was on lowbeam) the light did not work, nor was there a camera like "flash" like the filament burned out. It acts like something is burning out the bulb BEFORE I turn it on the next time I use it. Maybe the voltage regulator is set too high or something???

 

I had a 1996 lt160 and i had the same problem. I also replaced the bulbs, but mine had a short in some wire that i finally got fixed.