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Tinkerer
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572 Posts
Discussion Starter #1
Hi all, only bought my vulcan last week, the previous owner said that he'd had the bike checked over by auto-spark and the R/R & Stator where both working 100%. I'd no reason to disbelieve him as I wasn't aware of faults on the vulcan until joining this forum.

Anyhow, the previous owner added Dominator style headlights and aftermarket indicators/flashers. I took the bike out for a spin on saturday and the headlight stopped working, never thought much of it at the time as the wiring looks ropey to say the least and I plan on putting the stock headlight back on.

Spockster mentioned that I should check the voltage output as the headlight is linked to one leg of the stator.

First opportunity I got was today, checked the voltage on the battery and it drops down to 9 -10 volts when the engine is revved, so it ain't charging when its running.

So I assume the the R/R is shot? I'm just really hoping the Stator isn't fubar'd to :(

I'll get out into the shed for a while tomorrow and have a look at the stator... I preparing for the worst, scrap stator and hoping for the best... a new R/R needed...

Nothing like being dropped in at the deep end :BLAM:

If anyone has any hints/tips/suggestions I'mm all ears :)
 

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1986 VN750
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3,255 Posts
What you need to do is test each component separately with a multimeter.

Do a search on here, we have docs for each under Electrical.

Quick Rundown on stator test: Test AC voltage between all 3 legs of the stator (2 at each time, you'll have to test 3 times to test them all). You'll want to see voltage the same across all the legs of the stator, as low as 20v idle and as high as 90v @ 5k rpm (want to see above 50v @ 5k rpm). If you notice one leg of the stator has way less power than the rest, the stator is shot. Also test continuity to ground, each leg should have NO continuity to ground, if it does, the stator is shot.

For the regulator: http://www.electrosport.com/technical-resources/library/diagnosis/pdf/diode-testing-guide.pdf

Edit: Also charge up the battery, maybe have it tested. A bad battery can mimic a bad charging system.
 
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Tinkerer
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572 Posts
Discussion Starter #3
Cheers thtanner for the advice... I've got a new AGM battery to collect tomorrow. So i'll try that first, If it's still dropping voltage, I'll try the other tests. Thanks again, Gaz
 

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1986 VN750
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163 Posts
Also, if there is a voltage draw or short somewhere, the headlight relay may not be closing. If the R/R, stator, and battery check out ok, check for a parasitic draw (amperage going through the battery circuit with the bike off and key out) or a short by the headlight. Sometimes the auxiliary line gets pinched in the fork stops..
 

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Tinkerer
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572 Posts
Discussion Starter #5
Cheers Mike, I'll give that all a try tomorrow.

I managed to collect my AGM battery and dropped it in. Voltage still dropping on a rev, although on the new battery its dropping from 14+ to 13.79 volts.

Hopefully have an hour or two to myself tomorrow and will get to the bottom of it, thanks for all the help guys.
 

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Registered
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459 Posts
I agree that I wouldn't jump to assuming the worse. Follow the instructions. Could be a simple R&R or excessive load. Pull the fuses out for the non-essentials when testing.
 

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FREEBIRDS MC CENTRAL NY
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16,076 Posts

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Tinkerer
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572 Posts
Discussion Starter #8
Cheers folks I'll go through everything and run the tests you suggest. Unfortunately I could write everything I know about motorcycle electrics on the back of a postage stamp lol.
 

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Tinkerer
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572 Posts
Discussion Starter #9
Didn't get the time in the shed as I hoped for, but got 10 minutes to myself and nipped out.

I put the voltmeter across the battery terminals first to see what the new AGM battery was like after being left in the bike overnight. 12.4v

I didn't have enough time to check the stator or R/R (fingers crossed tomorrow)

I forgot to mention that one of the 10amp fuses was blown yesterday, I replaced it and the headlight worked again (its a miracle lol), however after reading the about the blue wire in the JB I done that just now.

I started the bike up and on idle the battery was reading up to 13.57v on the voltmeter however when revved, she's dropping as low as 5.34v :surprise: so quite a big drop compared to last nights test.

Anyway, tomorrow is another day and I'll check everything and report back
 

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1986 VN750
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3,255 Posts
5v when revved? Can't believe it stayed running! Wow
 

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Sparky!!!
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8,696 Posts
Didn't get the time in the shed as I hoped for, but got 10 minutes to myself and nipped out.

I put the voltmeter across the battery terminals first to see what the new AGM battery was like after being left in the bike overnight. 12.4v

I didn't have enough time to check the stator or R/R (fingers crossed tomorrow)

I forgot to mention that one of the 10amp fuses was blown yesterday, I replaced it and the headlight worked again (its a miracle lol), however after reading the about the blue wire in the JB I done that just now.

I started the bike up and on idle the battery was reading up to 13.57v on the voltmeter however when revved, she's dropping as low as 5.34v :surprise: so quite a big drop compared to last nights test.

Anyway, tomorrow is another day and I'll check everything and report back
I have seen this before.. quite a few times.. simple and easy fix.. there is a ground wire that runs from the battery box to the transmission on the brake side of the battery box. I see the bolt on the transmission backs off just a little bit allowing corrosion in there. So minuscule amount almost not able to see it, but its enough to cause a bad ground.. as the Stator starts generating voltage it opens up that gap and the ignition system and headlight end up eating all the battery voltage. Just pull off the cable, clean the cable eyes and the mounting surfaces on both the transmission and battery box and you should be fine.
 

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Tinkerer
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572 Posts
Discussion Starter #12
I have seen this before.. quite a few times.. simple and easy fix.. there is a ground wire that runs from the battery box to the transmission on the brake side of the battery box. I see the bolt on the transmission backs off just a little bit allowing corrosion in there. So minuscule amount almost not able to see it, but its enough to cause a bad ground.. as the Stator starts generating voltage it opens up that gap and the ignition system and headlight end up eating all the battery voltage. Just pull off the cable, clean the cable eyes and the mounting surfaces on both the transmission and battery box and you should be fine.
Cheer Slim, I'll do that today and report back. Appreciate your advice :smiley_th
 

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Tinkerer
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572 Posts
Discussion Starter #14
I have seen this before.. quite a few times.. simple and easy fix.. there is a ground wire that runs from the battery box to the transmission on the brake side of the battery box. I see the bolt on the transmission backs off just a little bit allowing corrosion in there. So minuscule amount almost not able to see it, but its enough to cause a bad ground.. as the Stator starts generating voltage it opens up that gap and the ignition system and headlight end up eating all the battery voltage. Just pull off the cable, clean the cable eyes and the mounting surfaces on both the transmission and battery box and you should be fine.
Cheers Slim :notworthy:notworthy:notworthy:notworthy

Did what you said, all sorted. :smiley_th

sitting at 13.75 on idle, 14.51 when revved

That's a big relief, unfortunately the 9v battery on my voltmeter died, so I'll not get to check the R/R and stator until later.
 

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Sparky!!!
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Cheers Slim :notworthy:notworthy:notworthy:notworthy

Did what you said, all sorted. :smiley_th

sitting at 13.75 on idle, 14.51 when revved

That's a big relief, unfortunately the 9v battery on my voltmeter died, so I'll not get to check the R/R and stator until later.
glad my advice helped.
 
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