Keep blowing headlights

SO i have had the bike for about 9 months now. and ever since i have had it it will blow head lights like every 2-3 weeks. it will blow the reg so i switch to the bright but it will blow shortly after. it's never been while i was riding at least not at night it seems like it's when i start it or something like that. b/c it will be working when i get home at night and not when i go to leave in the morning. i replaced the separate rectifier regulators with a combo unit 2 weeks ago. but the bulb blew gain 2 days ago. if you look at the bulb the filament is usually broken at one side or completely detached. The bike doesn't have any turn signals and it blew the high beam indicator bulb in the cluster about a month after i got it.

Should i be looking for some type of short in the wireing harness?

thanks guys Rob Johnson

I'd check the battery connections especially the ground cables(the heavy gauge ones)What is the battery voltage at idle and at 4000 rpm? if it's over 14 volts at 4k the regulator/rectifier may be faulty or if the brown sense wire is out of the circuit.

Check all the connections from the regulator/rectifier for corrosion and tight joints. Any loose pins in the connectors can cause voltage surges.

thanks i'll start there. and let you know what i find

if you do have a short in a lighting circuit, it will use the bulb as the fuse

This does not sound like your problem,but vibration can blow them too. i had to weatherstrip and caulk inside my light to dampen the bad vibes.

No turn signals? Sounds to me like it could be a short somewhere with the turn signal wires. Make sure the connections at the fuse box are clean and in order. If the fuse box gets hot then for sure. The white wire usually looks brown or the fuse box melted a bit. If the fuse box is shot don't replace it with the same type go for the automotive square fuses used today as they run much cooler than the old bulb type fuses.
I had this problem with my 80 and the headlamp was causing the short and blowing my main fuse. I found the wire loose in the headlight bucket as well as a loose bucket because of dry grommets. I would go to start it in the morning and headlight wouldn't come on then I would tap it or it would come on later causing the fuse to burn while I was on my way to work. It was frustrating because after I had fixed it one of the bulbs I replaced it with also had a short that really bewildered me until someone told me that light bulbs get shorts too.
Scary stuff considering being stuck in traffic on a major highway with no emergency lane.
My fix was easy but took me a while after to realize that the light bulb was the culprit. Once I replaced the bulb and made sure the wires were nice in the place they were supposed to be in and such I never had another problem again.
Electrical stuff is extremely frustrating.
You have to make sure that all the wires are where they are supposed to be and that they are clean and tight and the headlight isn't bouncing up and down as sometimes happens when the grommets dry rot after so many years and well.... for sure all of these things are probable problems now. The ignition switch could be faulty the turn signal switch could be the problem the fact there is no signals hooked up. Make sure the key doesn't move around like a two dollar hooker. It should click firmly into place if it's loose will cause a short. Maybe turn signal wires are touching and causing a short somewhere.
My neutral safety switch had a slight baring of the wires causing my left signal light to burn out all the time and once I got the shock of my life one day trying to kick it over which is when I looked at the wires really closely. The battery connection to the battery could be all ratty causing a short. Easy fix buy a new one from z1. If you have a 79-80 ignition switch will be difficult as they don't make repro's of those and the pre 79 doesn't have the right amount of wires. Learned that the hard way as well as ordering a new fuse box they are different too and will need modifying at which point better to modify it to a newer updated configuration.
Good luck on that one and hopefully it is the easiest of all explanations that the turn signal wires are causing the havoc and nothing expensive to fix.

mark1122 wrote:

This does not sound like your problem,but vibration can blow them too. i had to weatherstrip and caulk inside my light to dampen the bad vibes.

Bang on correct!
(not saying that it's NOT an electrical issue,but...)
I had the exact same thing going on with My bike a few years back,and it turned out to be a vibration issue.
So I made some new grommets for the bucket and problem solved!

The way my bucket was attached,there was a point where there was no grommet in between the 2 particular metal parts.I put some rubber in between and it solved it.
Good luck.

i think it's time to check the charging system output. sounds like overcharging to me. warm up the motor to operating temp. then check the battery voltage between the posts with a multimeter. at 4000RPM the voltage should be 14.5v. also touch the reg/rec if it's uncomfortable to the touch you have too much resistance in the wiring somewhere or everywhere. or worst case the reg/rec is toast. if it's worst case. you will still need to clean every connection fuses, switches, battery posts, motor grounds. skip this step and a new reg/rec will fail soon too. remember the bike is 29 years old and corrosion has set in.

Is your headlight really really bright? It will naturally brighten slightly from idle to about 4000 RPM or so and then nominally remain that brightness to redline.

The fact that your indicator bulb blew tells me there is an over voltage condition. How is your battery? Does it turn over the engine on electric start? If not it may be failing and causing the regulator to allow too much voltage into the electrical system. This may end up damaging the ignition system as well.

This happened on my KL250 many years ago as I allowed the battery to get real dead since it is kick start only. The battery finally shorted internally and the regulator spiked up probably in excess of 20 volts on a 6 volt system and it blew out every bulb on that bike. I had a heckuva time finding bulbs locally but I did replace them all and the battery as well. I never had another problem as I replaced the battery before it got that weak again.

I am another that has had that problem, on 2 bikes, both times it was vibration problems, I got tired of bringing an extra headlight and tools on night rides so I homemade some vibration dampers out of a tire tube for the headlight bucket and never had a problem since. I would take pics but I don't own either of these bikes anymore.

I agree, this would be a bad voltage regulator. Eventually this will also destroy your battery and can also blow your ignition. Change the voltage regulator. 14v across the battery terminals is ABSOLUTELY MAXIMUM. For me that is also a bit too high. Kawasaki states 14-15V. 14 makes me more comfortable. Charging voltage for a lead acid battery should not be more than 12% over rated voltage =13.44v.

otakar wrote:

I agree, this would be a bad voltage regulator. Eventually this will also destroy your battery and can also blow your ignition. Change the voltage regulator. 14v across the battery terminals is ABSOLUTELY MAXIMUM. For me that is also a bit too high. Kawasaki states 14-15V. 14 makes me more comfortable. Charging voltage for a lead acid battery should not be more than 12% over rated voltage =13.44v.

i disagree with you, the charging amperage should not be more than 12% of the amperage rating of the battery. new cars have charging voltages that can exceed 14 volts. as to the the bulbs. many 12v bulbs can easily live at close to 17v+. you have resistance somewhere in the wiring. you have corrosion. first clean the battery terminals and their wire connects. then the positive wire from the battery where it connects to the fuse box and starter solenoid. next trace the neg. battery wire to where it connects to the motor cases and clean that connection. last locate the black wire from the rec/reg clean it and make a jumper wire to the neg. post of the battery from where the reg/rec ground is landed. that should reduce the high voltage. however you still need to go thru all the wiring and clean and snug up all the connections. now test the charging system output.