Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums - Reply to Topic
Where does this wire go?
Includes Electrical mods, Lights, Stator,
Rectifier, Diagrams, etc

Thread: Bike only runs when starter button is pushed in Reply to Thread
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  Topic Review (Newest First)
10-03-2017 09:45 PM
willyb99 No, I decided to pull it and cut it open (I tried to post a pic). I gave it a quick brushing and now it does nothing! That's ok, I had it in my mind I had to get anyway. I had wondered that it actually worked properly because I could not get the starter to engage. I checked all the interlocks, grounded pin 5 in the CDI. Nothing. I did not try to jump the starter solenoid. Hopefully I can get one soon as it's starting to get cold here.
10-03-2017 08:48 PM
Originally Posted by willyb99 View Post
Well if I didn't need a CDI, I do now.

Did the magic smoke leak out?
10-03-2017 07:21 PM
willyb99 Well if I didn't need a CDI, I do now.

10-03-2017 01:16 PM
Spockster 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.
10-03-2017 12:50 PM
willyb99 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.
10-03-2017 12:22 PM
TonyO 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)
10-03-2017 12:14 PM
Spockster 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.
10-03-2017 11:55 AM
michiganteddybear 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
10-03-2017 11:25 AM
TonyO 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.
10-03-2017 11:20 AM
michiganteddybear 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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