Bike only runs when starter button is pushed in - Page 2 - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
Electrical
Where does this wire go?
Includes Electrical mods, Lights, Stator,
Rectifier, Diagrams, etc

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post #11 of 21 (permalink) Old 10-03-2017, 09:11 AM
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Do you think our mystery wire to the CDI could be a retarder? Would make sense to retard the timing while the button is pushed.

'99 Vulcan "Victoria"
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post #12 of 21 (permalink) Old 10-03-2017, 11:20 AM
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I have always suspected that wire from start button to CDI box was to affect ignition timing in some way.

I have had mine when hard to start (flooded or on a REAL humid morning) act somewhat like yours, in that I had to hold start button in while giving a bit of throttle (engine is trying to run) until it cleared out the jugs. usually just a couple seconds is all it took

since we have no distributor with advance for the timing, all the timing adjustments must be done electronically, based on rpm only, and the CDI takes care of this

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post #13 of 21 (permalink) Old 10-03-2017, 11:25 AM
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Are there timing marks on the bike anywhere? Would not be too difficult to test the theory with a timing light and rigging up a way to input 12v to the CDI blue wire.

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post #14 of 21 (permalink) Old 10-03-2017, 11:55 AM
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if I recall, there are timing marks on the flywheel, what you would reference them to I dont know, there is no pointer or scale. you would be able to access them from the cover over the pickup coils, but there is a fair amount of oil flinging around there when its running.

needless to say, because its 'unadjustable' per kawasaki,, they made no way to really see them

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post #15 of 21 (permalink) Old 10-03-2017, 12:14 PM
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That's what I figured, the wire alters timing during starts. But advance is best for cold starts and retard is better for hot starts.

Since the CDi does have a start circuit, and the bike only runs with the start button pushed, I would suspect the CDi or some wire/plug running to it .

The wire in question isn't blue, but I forget the color, yellow/red? It doesn't pin out from the JB, the diagram shows it as a branch from the start button circuit midway of the harness. I did find it at the CDi, but didn't get to where it connects to the harness.

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post #16 of 21 (permalink) Old 10-03-2017, 12:22 PM
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Apart from the oil issue this seems simple.

Start bike and use timing light to set a baseline for timing by marking case where the flywheel mark gets flashed.
spoof the CDI by putting conecting blue wire to CDI (disconnect starter or relay so starter does not engage)
mark where the new timing occurs on the case.
If they are different then the blue wire affects timing, the where will indicate advance retard and approx value
repeat step one to make sure timing goes back to previous value (JIC the CDI has some other retard/advance function such as power on time)

'99 Vulcan "Victoria"
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post #17 of 21 (permalink) Old 10-03-2017, 12:50 PM Thread Starter
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Just after I posted this i did find a few pics of the insides (as well as the video posted) I see a few heavy duty diodes that my be the culprit. I guess I'll have to get a CDI one day and if that one works, I'll take the original apart and do a few tests on various components.
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post #18 of 21 (permalink) Old 10-03-2017, 01:16 PM
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I'm a bit lost on the blue wire at the CDi. But will study the diagram when I have more time, I noticed I need to fix my pics in the Two-Wire thread.

The branching wire to the CDi I've focused on is yellow/red according to what I posted in the 2-wire thread.

TonyO, that sounds like a good way to see what happens during start.

willy, if you can get the links for those pics, Thorn can probably make good use of them, he's a pretty sharp egg on electrical.

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post #19 of 21 (permalink) Old 10-03-2017, 07:21 PM Thread Starter
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Well if I didn't need a CDI, I do now.

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post #20 of 21 (permalink) Old 10-03-2017, 08:48 PM
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Quote:
Originally Posted by willyb99 View Post
Well if I didn't need a CDI, I do now.

Did the magic smoke leak out?

2003-21k mi
Shaved w/UniPK92+Stock Jets-TPE/MOSFET-Shinko Tires-AGM batt-bags-chrome-LEDs...more
__________________________________________________ ____________
Repair Manual: http://www.mediafire.com/file/mj7z81..._Catalogue.pdf

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