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Discussion Starter #1 (Edited)
Edit March 2016: So far, we know Kawi used black/red or all black for the wire running to the 10-pin JB plug from the start button. This has caused some confusion and errors applying this mod in some cases. This is probably the reason for the headlight problems later in this thread. Will try to get a couple of pics and pin locations up as soon as I can post pics again.
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Edit June 2017 - Watch this video before beginning: http://www.vn750.com/forum/19-electrical/94698-short-video-blue-wire-two-wire-mods.html

* Be aware that this mod disables the neutral start switch. Your bike will start in gear with the clutch engaged after doing this mod.*

Posting this so more people may become aware of it, recommending it as a preventative mod that could save your stator, or resolve some of the other problems it covers. The mod can also keep you from being stranded.

The Two Wire Mod

1) At the Junction Box, find the 10-pin connector (smaller of the two)

2) Locate the yellow/red stripe and black/red stripe wires (Kawi also used all black instead of black/red)

3) Remove the two wires from the 10-pin plug

4) Splice the two wires together securely and insulate properly

edit: This is the color diagram I'm using:



Link to High-Res Color Wiring Diagram: https://drive.google.com/file/d/0B23DfMXHXUWiS1JkcWRmQ2dzMGs/view

That's it!

What The Two Wire Mod Covers

1) Start Button Failure

2) Low Peak Charge Voltage

3) Charging System Brownouts - (volts dropping well below peak voltage for periods of time)

4) Charging System Failure to charge with a good stator, R/R, etc.

5) Possibly improves ignition voltage. The yellow/red branches off before the Junction Box and feeds into the IC Ignitor box. Hot and cold starting both improved on my bike.

This mod is bypassing unidentified faults and future faults with these circuits in the Junction Box.

Let us know if this works for you.

michiganteddybear did this 1 1/2 years ago for his start button.

I have the TPE/MOSFET and this mod cured charging system brownouts, low peak charge, dead start button, and hot/cold starts on my bike.

thtanner has the TPE/MOSFET that wasn't charging at all, both of ours are at 14.5v now.
 

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FREEBIRDS MC CENTRAL NY
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Sticky Sticky Sticky Sticky Sticky Sticky Sticky Sticky
 

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Discussion Starter #3

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I first did this mod due to the start button intermittently failing to crank engine.. a couple well placed whacks on the left side cover (where junction box lives) sometimes brought life back to it.. traced it back to a failing start relay inside the J/B. The mod has totally removed that issue from my bike.

on a side note, and it wasn't checked at the time (not a concern when I did mod), I don't know what my charge voltage was, but I have stock oem stator, and at that time the stock oem r/r. since the mod I have replaced the r/r with a mosfet (still have stock stator), and I believe my charge voltage is around 13 at idle, but climbs to 14+ by the time its turning 2k rpm..
 

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FREEBIRDS MC CENTRAL NY
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Thank you
 

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Discussion Starter #7
MTB, I wouldn't have known about the voltage changes without the dash mounted volt meter. Might never would have connected the increase in volts with doing this mod, I also just needed the start button working again.

Thanks for the quick sticky.

Spread the word folks, I think this will help a lot of riders. I'd say it ranks somewhere on the list of things to do when you first bring your Vulcan home, because it could prevent ever having these problems. On the list with checking spline lube, etc. Add to The Verses?

Don't know who might have discovered this bypass first, but I figured it out for myself and as soon as I mentioned it, MTB confirmed it worked for him 1 1/2 years earlier. I then knew to proceed with cutting those wires. Thanks again, MTB.

If anyone sees a mistake in the write-up, or comes up with more info, we'll edit it into the first post as well. Wasn't sure what to call it, JBStarChargVI or JBSCVI (junction box start charge volts ignition) seemed too much, The Two Wire Mod sounds simple, as it is to do.

It's possible this mod might make the ign. coil relay mod obsolete. That yellow/red shorting in the JB, may be responsible for the voltage drop through the yellow/red to the IC and then to the coils. Or the improved voltage on the yellow/red at the IC provides better spark timing adjustment on cranking. I'm just not sure.
 

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without having an internal schematic of the ignitor box, there is probably no way we will ever figure out what happens when the start button is pressed. we can speculate due to what we see happening, but thats about it.

almost makes me want an old one to disect and reverse engineer.
 

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Discussion Starter #9 (Edited)
KC2 has repaired some JBs, he may have something to add if he sees this. Haven't seen him for a few weeks though.
 

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No Headlight

So I did this mod and now my headlight doesn't come on. No low beam or high beam and no warning lights on the dash. I'm know my light was working yesterday. My bike is stock otherwise, can someone help me?
 

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Discussion Starter #11 (Edited)
So I did this mod and now my headlight doesn't come on. No low beam or high beam and no warning lights on the dash. I'm know my light was working yesterday. My bike is stock otherwise, can someone help me?
You may have uncovered some info we need for doing this mod.

On mine, I already had the blue-wire headlight relay bypass in place, so I had no trouble with the headlight. Not sure how MTB or tanner has theirs set up.

You may need to move the blue wire for this mod to work. We'll see.

Meanwhile, verify that you got the correct pair of wires off the 10-pin plug. Make sure you didn't cut the solid yellow wire that triggers the headlight relay.
 

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I also have the headlight wired stock, my light comes on.

Check the 3 stator wires and make sure one did not get disconnected as well.
 

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I cut the correct wires, I triple checked the colors before I snipped them. I didn't have much time to mess with it before I had to leave for work. I will try reconnecting the wires and see if my headlight works. what is this headlight wiring mod?
 

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Discussion Starter #17 (Edited)
Also be sure you used the 10-pin for the The Two Wire Mod and not the 8-pin, the plugs have both colors on them.

Correction: The headlight bypass moves the blue wire on the 8-pin plug, and moves it to the empty slot on that same connector. (empty slot is directly beside the blue wire)

You need to release the locking tab on the spade with a stiff wire or pin. It will lock into the hole when you push it back in.

There's more info and a video on this thread:

http://www.vn750.com/forum/19-electrical/49946-blue-wire-bypass-headlight-relay-mod.html
 

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just for giggles and grins, this morning I went out and checked voltages on my bike.. I have had a little slow cranking in the morning than in the past (I suspect battery is getting weak).

ign off.. 12.4
ign on.. 12.1
during crank.. 10.1 (give or take a tenth)
idle (at 1k).. 13.9
2k rpm.. 14.00
and all the way up to 4k.. 14.00

remember, I have stock stator, and mosfet. to me it seems like my mosfet is limiting output to 14 volts (which will still charge battery plenty well).

again, main reason I tested was to verify the charging system was working properly, and to verify my suspicions of a weak battery (its at least 3 yrs old, think more like 5).
 

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I double checked my cut wires and I cut the proper ones. If I connect them back together the headlight comes on like normal. Connected together the bike will start, but no headlight. I got the 8 pin connector out, how does the 10 pin one come out? I want to put it back together like stock.
 

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Discussion Starter #20 (Edited)
Correction: The headlight bypass moves the blue wire on the 8-pin plug, and moves it to the empty slot on that same connector. - 8 pin - (empty slot is directly beside the blue wire)
Repeat:

Correction: The headlight bypass moves the blue wire on the 8-pin plug, and moves it to the empty slot on that same connector - 8 pin -. (empty slot is directly beside the blue wire)

You do not move the blue wire to the 10-pin.

What year is your bike, first time? Baffled why this didn't work on yours. Are you able to post any pictures of the wires in question?

To answer your question, the 10-pin comes out the same as the 8-pin. The plugs just get stuck tight. Have to release the lock and wiggle the plug.
 
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