Headlight bulb burning out quickly

[mitchell]

I do park facing East but...
I ran a wire direct from the ground 'sleeve'(where the orange wire slips in from the left handlebar control) and direct to the neg battery terminal. Same result. At idle, the bulb looks fine. When i increase the throttle, it burns out in a couple of seconds. Now I am out of bulbs. $40 in bulbs in a week. Is there a way to check it without risking another bulb???

[mrunderhill1975a]

You can test the circuit using a multimeter rather than using more bulbs.
Ok, we need to start at the beginning.  1)Do you have a 3 wire or a 4 wire alternator?
2) When you attach a multimeter to the headlight contacts, are you getting Alternating Current or Direct Current?
3) What is the voltage of the headlight connections with the engine at idle and what is it with the engine revving?
4) In addition to the "combination " regulator/rectifier you have installed, Is there a small black voltage regulator (approx 1"x 1"X 1.5")llocated somewhere  (not the turn signal flasher and not metal regulator, but a separate regulator encased in black plastic)?

[mitchell]

So I finally got some time to get into it again. No luck. I brought it to a recommended mechanic who is a harley whiz. He spent some time for me looking over what work I had done and gave me a few things to look for yet again. But just before i was leaving, he moved a nest of wires around and says, 'what's this?'
I look in there and see a small a/c regulator with a burn hole in it.  !  I mean mounted on the side of the rear mudguard and nestled just in from the toolbox 6" from where I had been working to install the new a/c voltage reg/rect and all the rewiring/soldering and remounting I had done. Like it had just manifested itself there. How could I have missed it?!
Because the bike kicks and runs with it unhooked, it appears to be a dedicated headlight regulator. I never knew the bikes had one.
The writing on the part says:SWISS AC REGULATOR 12 V. And on one side: SAP-816 Bullet Machismo DIESEL 09-06-2010.
So, I have a new on order from enfieldparts and should get it any day now.
Question: What might have caused it to blow, so I can avoid burning the new one ($40) and is mounting it on the mudguard an effective ground?
Thanks All,
Mitchell
 

[mitchell]

I replaced the headlight regulator, mounted it to an aluminum bracket  and ran a new ground wire from the headlight socket to the connector, put in a new bulb and it works perfect!
Thanks to all for your help,
Mitchell

[LarsBloodbeard]

Question: What might have caused it to blow, so I can avoid burning the new one...

Glad you got it rectified.

To answer your question, many things could cause it to fail.  But the only reason it would burn up like that is if it had an internal short or a component catastrophically failed.  It could have been a manufacturing flaw.  It could have been shorted between the external terminals.  A voltage spike could have damaged an internal component.  It may not have been sealed properly and water or something got into it.  Etc.

[mitchell]

Thanks Lars. I am guessing/hoping that it was just a poor quality item and the new one will be better...for awhile. I also feel more confident that running a new ground wire avoids a relapse.
Mitchell

[forrestt]

This sound like the kind of thing that would happen to me. ...hope you got it sorted.