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ZZ4Blazer

Headlight voltage

8 posts in this topic

What kinda voltage should I be seeing at the headlight?

After blowing a couple bulbs, I finally tested the socket and was showing like 30 volts. Bad regulator, was replaced.

Low beam was burnt out already, didn't have time to order another bulb before previous ride. So was just gonna run high beam. Which, burned out shortly after beginning my trail ride.

Im hoping the bulb was damaged from having the high idle voltage.

Im showing 10 volts at the headlight at idle, dropping to 7.5 by 5k rpms. Both reving in neutral.

Running Im showing 14.2ish at the battery. 12.90 to the tail light while running.

Ive been through a bunch of the threads, and looked through the manual and don't have any real clear answers.

Other than the headlight, bike runs awesome, no stumbling, starts quick on first kick or couple cranks of the button.

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Should have the same voltage as the battery with the engine running I think. 13.5-15v would be acceptable I think. I'm no electrician though

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Should have the same voltage as the battery with the engine running I think. 13.5-15v would be acceptable I think. I'm no electrician though

All things being perfect, yup, should be the same voltage. More than likely you'll have a slight drop of a half a volt to a volt in practice though.

Sounds like a voltage reg problem still. I know you replaced it but was it a new Yamaha factory one or used? What are the odds your bike has a modified stator to run everything DC? If its been modded, the stock RR will not work.

The 12.9v at the tail light sounds right on, but the headlight should be the same. The original bad RR may have been a symptom of a larger problem and not the actual problem. Do some digging per the manual, sounds like you may have something dragging down the headlight system.

You measuring DC or AC at the lights? Should be AC on a non-modded stator and should not drop more than a half volt at 1/2 throttle.

Edited by miweber929

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Battery voltage will not be the same as the headlight voltage, as they are not on the same circuit.

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The regulator/rec was a new factory unit.

I had a problem that I wasn't getting power all the sudden to the socket. Traced it to a broken wire down in the harness. Wire changes color down under the tank, and theres a factory connection there and that was broken. I think that broken wire, caused the regulator to crap out. Wire was soldered together, then afterwards found it was running like 30 volts at the headlight.

I believe everything is stock. Bike is new to me this year.

Meter had to be switched ac/dc to check the battery vs the headlight, so I know they are still on different circuits.

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Battery voltage will not be the same as the headlight voltage, as they are not on the same circuit.

Well yes, but they still should be approximately the same value, though DC on the battery and AC at the light. Sorry, should have specified that more clearly.

The regulator/rec was a new factory unit.

I had a problem that I wasn't getting power all the sudden to the socket. Traced it to a broken wire down in the harness. Wire changes color down under the tank, and theres a factory connection there and that was broken. I think that broken wire, caused the regulator to crap out. Wire was soldered together, then afterwards found it was running like 30 volts at the headlight.

I believe everything is stock. Bike is new to me this year.

Meter had to be switched ac/dc to check the battery vs the headlight, so I know they are still on different circuits.

Sounds stock but 30 volts at the light indicates a bad RR. Was it replaced before the broken wire was found? Hooked up exactly the same? May want to have the shop you bought it from or a local alternator shop to test. Manual may have a check in it as well, mine is not by me or I'd check the procedure.

Mike

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What kinda voltage should I be seeing at the headlight?

After blowing a couple bulbs, I finally tested the socket and was showing like 30 volts. Bad regulator, was replaced.

Low beam was burnt out already, didn't have time to order another bulb before previous ride. So was just gonna run high beam. Which, burned out shortly after beginning my trail ride.

Im hoping the bulb was damaged from having the high idle voltage.

Im showing 10 volts at the headlight at idle, dropping to 7.5 by 5k rpms. Both reving in neutral.

Running Im showing 14.2ish at the battery. 12.90 to the tail light while running.

Ive been through a bunch of the threads, and looked through the manual and don't have any real clear answers.

Other than the headlight, bike runs awesome, no stumbling, starts quick on first kick or couple cranks of the button.

10 volts sounds too low (may be joined badly), 30-V is too high, it should be closer to 12-VAC.

Edited by Barra8

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Finally got some time tonight to work on my bike. got the wiring under the tank exposed and sorted a bit. Im getting the same 10ish volts at the headlight via the green wire.(and dropping as the rpms come up) Green turns into yellow as it heads down the frame and spits off. One of the yellow wires goes to the rectifier, the other goes down to the mag. Have the same voltage at the rectifier yellow wire, as coming right up from the magneto.

The other wire coming from the AC side of the mag is a white wire. According to the manual the yellow is the lighting ciruit, the white is the charging. Got a nice 12.8ish with the white wire.

I cant seem to get a reliable reading on the AC side of the mag when trying to ohm it. However, the DC side is right in the middle of the specs.

Ive still got my old bad rectifier, I might throw it on and see what that's reading again and compare.

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