« previous next »
Pages: [1]   Go Down

Author Topic: Tail light keeps burning out  (Read 3886 times)

0 Members and 1 Guest are viewing this topic.

Offline Davez134

  • Expert
  • ****
  • Posts: 1,485
Tail light keeps burning out
« on: June 12, 2012, 08:42:58 PM »
I have a 1972 CB750. When I got the bike earlier this year I got a brand new wiring harness, as there were more cuts and splices from previous tail light/turn signal modifications than I was comfortable with. I wired according to shop manual, checked all wires that plug into harness for damage, and ended up with everything where it was supposed to be per the diagram. all electrical is stock on bike with exception of tail light housing, but I'm using the correct bulb (12v 7/23W). After every couple days of riding I'm noticing that my tail light (smaller filament) burns out while brake light still works fine. I figured it might be the voltage regulator so I adjusted the gaps in it per the manual and tested it using a multimeter. Battery voltage read 12.2 at idle (around 1000 rpm) and never went over 14.2 at 4000-5000 rpm. (although I only left it in this rpm range for maybe 25-30 seconds). It burnt out again today. Am I way off? Anything I'm missing or doing wrong? Please help I'm going crazy and electrical is not my forte. Thanks!
Logged

Offline Bodi

  • Really Old Timer ...
  • *******
  • Posts: 5,772
Re: Tail light keeps burning out
« Reply #1 on: June 12, 2012, 09:12:24 PM »
You say you have the correct bulb, are you sure? Voltage looks good.
I've found that auto store brand lamps can die from the vibration of bike use in a few days. "Name brand" lamps used to be better - but I don't know if there's any difference now, I think all the bulbs now come from the same factories in China. Possibly a bike dealer has the OEM Stanley bulbs, these were very strongly built with supports on the thin filament.
Or possibly something is causing more than normal vibration of the tail light?
Logged

Offline Davez134

  • Expert
  • ****
  • Posts: 1,485
Re: Tail light keeps burning out
« Reply #2 on: June 12, 2012, 10:30:46 PM »
I didn't even think of that! Seems like everyone is selling LED bulbs? Thinkmthis could be a fix?
Logged

Offline TwoTired

  • Really Old Timer ...
  • *******
  • Posts: 21,802
Re: Tail light keeps burning out
« Reply #3 on: June 13, 2012, 01:24:47 AM »
The stock tail lamp assembly has vibration isolation rubber.  Does your replacement housing have that?

Shake a hot filament hard enough and it will break.
Logged
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline d3buttz

  • More than just an
  • Hot Shot
  • ***
  • Posts: 290
Re: Tail light keeps burning out
« Reply #4 on: June 13, 2012, 07:44:18 AM »
It's a bad housing that's grounding your bulb out, or grounding elsewhere.
Logged
http://forums.sohc4.net/index.php?topic=80508.0

1975 cb750f
1975 cb550k
1972 cb350k
1974 tl125
1996 Nissan pathfinder
1972 Datsun 240z
2002 Nissan sentra se-r spec-v

Offline Blitzburgh207

  • Hot Shot
  • ***
  • Posts: 426
Re: Tail light keeps burning out
« Reply #5 on: June 13, 2012, 10:10:14 AM »
One time I hooked up the wires for the tail light and brake light backwards so I was running the brake light constantly and the tail light when I hit the brakes... this burned it out twice in a week or so before I realized what I did...
I think you said you got that though right?
Logged
1978 CB750 K8

Offline phil71

  • Master
  • *****
  • Posts: 1,813
Re: Tail light keeps burning out
« Reply #6 on: June 13, 2012, 11:40:07 AM »
If you have a regulator going bad, overcharging will blow bulbs in a hurry.
Logged

Offline LesterPiglet

  • Old Timer
  • ******
  • Posts: 4,045
  • 1977 CB550F2
Re: Tail light keeps burning out
« Reply #7 on: June 13, 2012, 11:41:39 AM »
Quote from: phil71 on June 13, 2012, 11:40:07 AM
If you have a regulator going bad, overcharging will blow bulbs in a hurry.

Just wondering would this affect one particular bulb or all of them?
Logged
'Then' and 'than' are completely different words and have completely different meanings. Same with 'of' and 'have'. Set and sit. There, their and they're. Draw and drawer. Could care less/couldn't care less. Bought/brought FFS.


Les Ross.            Certified by a Professional

Offline phil71

  • Master
  • *****
  • Posts: 1,813
Re: Tail light keeps burning out
« Reply #8 on: June 13, 2012, 11:58:08 AM »
Eventually, it would get all of them. except usually the brake and hi beam, cuz they're only switched on occasionally.
Blowing out Black, or looking like cateracts?
Logged

Offline Davez134

  • Expert
  • ****
  • Posts: 1,485
Re: Tail light keeps burning out
« Reply #9 on: June 13, 2012, 01:09:56 PM »
Thanks for the replies guys. I'm thinking its the mount as I can see how there would be a lot of vibration where it's mounted on my bike.  I know the taillight/brakelight wires are connected correctly and regulator seems to be working fine after testing it. Getting new led bulbs and msking sure it has some kind of shock/isolation mount. I'll update when I try this. Thanks again!
Logged

Offline cougar

  • Hot Shot
  • ***
  • Posts: 409
  • Stamping Ground, Kentucky U.S.A.
Re: Tail light keeps burning out
« Reply #10 on: June 13, 2012, 01:51:00 PM »
Davez ; While although my bike is not stock (my avatar) and it's been hardtailed. I completely rewired the bike myself. I had a problem with one of my elements in the brakelight unit breaking, I'm sure it because of all the vibration of it being hardtailed. The roads around aren't the smoothest in the world and my driveway is almost 4 wheel drive territory, so I was going through a couple of bulbs a week. I went to my local auto parts store and bought a 2 pac of LED bulbs, installed 1 and haven't had to replace a bulb since. The only possible problem that might come up is since the bulbs are Red all the time it lights my licence plate with Red light. Some places require a white light for you plates. Other than that I'll continue to run red LED bulbs. They're a little pricey but it will make up for it if your replacing blubs as often as I was.   ...cougar...
Logged
I'm not prejudice, I'll weld anything that pays! Knowledge that is shared is Never Lost!!   Right is right, wrong is wrong! The truth is the truth and a lie is a lie! DEAL WITH IT ACCORDINGLY !!!   I HATE "DIAL-UP"

Offline Davez134

  • Expert
  • ****
  • Posts: 1,485
Re: Tail light keeps burning out
« Reply #11 on: June 23, 2012, 05:46:21 PM »
LED's did the job. Thanks guys!
Logged

bollingball

  • Guest
Re: Tail light keeps burning out
« Reply #12 on: June 23, 2012, 06:30:54 PM »
Quote from: cougar on June 13, 2012, 01:51:00 PM
Davez ; While although my bike is not stock (my avatar) and it's been hardtailed. I completely rewired the bike myself. I had a problem with one of my elements in the brakelight unit breaking, I'm sure it because of all the vibration of it being hardtailed. The roads around aren't the smoothest in the world and my driveway is almost 4 wheel drive territory, so I was going through a couple of bulbs a week. I went to my local auto parts store and bought a 2 pac of LED bulbs, installed 1 and haven't had to replace a bulb since. The only possible problem that might come up is since the bulbs are Red all the time it lights my licence plate with Red light. Some places require a white light for you plates. Other than that I'll continue to run red LED bulbs. They're a little pricey but it will make up for it if your replacing blubs as often as I was.   ...cougar...

Cougar They make led bulbs that have red and white just for the tag in the same bulb. Try here  http://www.superbrightleds.com/

Ken.
Logged
Pages: [1]   Go Up
« previous next »