Engine dies when I turn the headlight on - any suggestions?

Electrical issues
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58kicker
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Engine dies when I turn the headlight on - any suggestions?

#1

Post by 58kicker »

Hi

I have a problem on my 1958 Panhead, that I have been struggling with for months now - the engine dies when I turn the headlight on (ignition switch position 2), if I leave the switch in position 1, I can drive for hours without problems.

Yesterday I went for a two hour ride (with no lights on), and when I returned and hooked up the maintenance chager, it indicated that the battery was fully charged.

The bike has a standard two brush generator, a new sealed 6 V/14 ah battery and new wirings and ignitions switch(6 pole replica).

I can't figure out, if this is a generator problem, a bad ignition switch, bad wirings/loose connections or if the headlight bulp on 35W/35W draws more amps than the generator can produce.

The GEN light on the dash never goes out - it keeps glowing with varying strength when I ride with the ignition switch in position 1, strange when I can ride for two hours and when I return, the battery is fully charged.

As mentioned, I have been struggling with these electrical problems for months now, and it's driving me mad - any suggestions on how to identify the problem is very appreciated.

Anders
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Re: Engine dies when I turn the headlight on - any suggestio

#2

Post by steve_wood »

The generator light seems to indicate a problem. Have you tried a new voltage regulator?
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Re: Engine dies when I turn the headlight on - any suggestio

#3

Post by 1950Panhead »

If your battery is still good (not dead) when the bike stalls your coil is not receiving the power it needs to work.
The coil gets power through pin 2 on ignition switch.
To test run a jumper from the + battery terminal to the + coil terminal then ride your bike and switch headlight on.
My guess is the bike will continue to run meaning your ignition switch is defective.

Another possibility (less likely) is you have a short in the headlight circuit.
With a direct short you usually smell burning insulation or find wires with no insulation.
Please report back.
Jerry
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Re: Engine dies when I turn the headlight on - any suggestio

#4

Post by 58kicker »

Hi Steve

I have an electronic regulator - I have not tried another one, is the any way to test the one I have, to determine if it's working as supposed?

Anders
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Re: Engine dies when I turn the headlight on - any suggestio

#5

Post by 58kicker »

Hi Jerry

Great idea - I will try that, and report back.

The engine will misfire almost instantly when I turn on the headlight, so this should be an easy way to narrow down the problem. When I turn off the headlight, I can continue riding without problems.

Anders
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Re: Engine dies when I turn the headlight on - any suggestio

#6

Post by Cotten »

58kicker wrote:....I have an electronic regulator - I have not tried another one, is the any way to test the one I have, to determine if it's working as supposed?..
Anders!

It is not uncommon for solid-state regulators to show a glow in the indicator light, even when charging properly.
Often it is an indicator of the battery's condition.

A comparison of the battery voltage running and stopped would be a partial test of the system;
A load test upon the battery may give a clue as well.

The switch is still the most likely suspect, or a misguided wire.
Normally OEM switches get worn to where they may not make contact without a jiggle.
They are easy to clean and service, by merely turning the contact bar to an un-worn portion.

....Cotten
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Re: Engine dies when I turn the headlight on - any suggestio

#7

Post by Bosheff »

Run a jumper wire from the from the ignition terminal on the ignition switch to the light terminal on the ignition switch with the motorcycle runnin and see what ya get. This should eliminate the mechanical end of the ignition switch as being the problem. If the engine continues to run with the jumper connected (lights working), ya probably got a problem with yer switch. If the engine dies, check out the wiring in the light circuit, including yer tail light wires....bosheff
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Re: Engine dies when I turn the headlight on - any suggestio

#8

Post by panhead rick »

direct short in one of your light wires
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Re: Engine dies when I turn the headlight on - any suggestio

#9

Post by Scrap »

Do you have a fuse or circuit breaker? A dead short would likely blow a fuse. Does the headlight work? How about the headlight on and the engine not running?
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Re: Engine dies when I turn the headlight on - any suggestio

#10

Post by 58kicker »

Hi

Did some testing tonight.

I measured the following voltage across the battery:

6,44 v - motor off, battery fully charged.
6,16 v - motor off, ignition switch in position 1(no light).
6,07 v - motor off, ignition switch in position 2(light on).
6,18 v - motor on, ignition switch in position 1(no light) at idle.
6,10 v - motor on, ignition switch in position 2(light on) at idle.
6,75 v - motor on, ignition switch in position 1(no light) at high rpms.
6,60 v - motor on, ignition switch in position 2(light on) at high rpms.

After this I detached the positive wire on the coil , and connected a jumper from the positive battery terminal to the positive coil terminal (as suggested by Jerry), and went for a ride with the lights on.

I rode for an hour with no problems at all, don't know if it was my imagination, but the bike felt stronger :)

When I got home, I measured 6,33 v across the battery (after 10 minutes).

So, does this mean that my ignition switch is defective, and there is nothing wrong with my generator and regulator?

Anders
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Re: Engine dies when I turn the headlight on - any suggestio

#11

Post by 58kicker »

Scrap wrote:Do you have a fuse or circuit breaker? A dead short would likely blow a fuse. Does the headlight work? How about the headlight on and the engine not running?
I have a fuse - the headlight works fine with the engine off or at idle, but if I switch the light on when riding, the engine will misfire almost instantly.

Anders
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Re: Engine dies when I turn the headlight on - any suggestio

#12

Post by 58bob »

I also had this problem, not fun when riding through the city in peak hour traffic, getting a bit dark, switch on lights....dead engine!
I had recently had the tanks off, and in my haste to go for a ride didnt get them set up level at the top to put the dash on. When i screwed the dash cover on it pressed (somehow) on the ignition switch causing the contacts to not touch when i switched the lights on.
With a dead motor i then turned on the ignition, red light, one more click to lights, nothing, took a spanner out and slowly undid the dash bolt and bingo, on came the light!........my issue sounds unique, (aftermarket tanks=crap) hope it helps.
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Re: Engine dies when I turn the headlight on - any suggestio

#13

Post by Hog54 »

Its the ignition switch.Mine does the exact same thing when I turn on the lights.I have to jiggle it to keep the bike running.Its almost like the contact area is dirty or has a coating on it or something.
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Re: Engine dies when I turn the headlight on - any suggestio

#14

Post by 1950Panhead »

So, does this mean that my ignition switch is defective, and there is nothing wrong with my generator and regulator?
Yes, clean, rotate (or replace) the brass pin in the switch.
Jerry
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Re: Engine dies when I turn the headlight on - any suggestio

#15

Post by awander »

58kicker wrote:Hi

Did some testing tonight.

I measured the following voltage across the battery:

6,44 v - motor off, battery fully charged.
6,16 v - motor off, ignition switch in position 1(no light).
6,07 v - motor off, ignition switch in position 2(light on).
6,18 v - motor on, ignition switch in position 1(no light) at idle.
6,10 v - motor on, ignition switch in position 2(light on) at idle.
6,75 v - motor on, ignition switch in position 1(no light) at high rpms.
6,60 v - motor on, ignition switch in position 2(light on) at high rpms.

After this I detached the positive wire on the coil , and connected a jumper from the positive battery terminal to the positive coil terminal (as suggested by Jerry), and went for a ride with the lights on.

I rode for an hour with no problems at all, don't know if it was my imagination, but the bike felt stronger :)

When I got home, I measured 6,33 v across the battery (after 10 minutes).

So, does this mean that my ignition switch is defective, and there is nothing wrong with my generator and regulator?

Anders
So you can turn the lights on with the bike running, at idle or high RPM, without killing the engine, as long as you are not riding?
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