Bike only runs when starter button is pushed in - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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Where does this wire go?
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post #1 of 21 (permalink) Old 10-01-2017, 11:04 PM Thread Starter
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Unhappy Bike only runs when starter button is pushed in

Hello!


Having trouble getting the bike to run on its own. I have seen many posts about this issue but it seems there isnít really a solution or fix for it. I have run quite a few tests I have come across some seem to be ok some donít.

Pin 14 on the JB, if I disconnect it and put a tester on it, should I connect to ground? I get nothing. However, if I turn on the key I get 9.8 volts. This wire connects to pin 5 on the ignitor which means it has 9.8 volts with key on. I have voltage on both coils when the key is on. Neutral light works as it should.

I broke the clutch switch (the little pin broke off) which means it is ďalways disengagedĒ The sidestand switch is questionable I do not have a spring for it. What is the easiest way to bypass these for testing purposes? Should I rig the clutch as pulled in? And the sidestand as up?

I cleaned out the start/stop switch but I am not sure how this would affect the stopping of the engine when I release the starter button.

The bike is all original with 0 mods (at least an ear shave in progress. I tested the relay coils and diodes in the JB (I did not test if the contacts within the relays conduct). Does anyone have any othere suggestions?? This is making me stabby
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post #2 of 21 (permalink) Old 10-02-2017, 12:03 AM
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I remember Spockster suggesting the two wire mod might fix this a few years ago in a similar thread but it wasn't tried

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post #3 of 21 (permalink) Old 10-02-2017, 10:01 AM
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Think I did suggest it before for this problem, but I'm not sure if it's the cure. There is a start circuit that runs to the CDi box, and we aren't sure what that wire does for starting. The Two-wire mod has other benefits that make it worth a try.

There's been other posts with the same problem but I don't recall a fix listed.

GM cars with points type ignition have the same problem when the 'condenser' or ballast resistor on the side of the coil goes bad.

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post #4 of 21 (permalink) Old 10-02-2017, 11:43 AM
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Pin 14 of JB will connect to ground via the interlock circuit, meaning grounded if any one of the following:
1. Bike is in neutral
2. Sidestand is up
3. Clutch lever is pulled

Each of those switches should be checked to make sure they are properly grounding. Neutral light coming on should mean the neutral sensor is working properly.

A stock bike WILL NOT START if the bike is in gear and the clutch lever switch is not activated. Since you can never activate your clutch, you will have to be in neutral to start your bike.

A stock bike WILL NOT KEEP RUNNING if the sidestand is down, the clutch is released, and the bike is in gear. It kills spark to the coils at the ignitor box. The start button DOES have an output to the ignitor box, and might override the sidestand lockout. I'm guessing that your mix of bad side-stand switch and bad clutch switch are creating a rare situation that lets the ignitor box provide spark when the start button is pushed, but cuts it off immediately when releasing the start button.

At this point, you could bypass the kickstand switch by jumpint the two wires that go to the switch (brown and green/white) and always start your bike in neutral (which you must be doing anyway), or do the 2-wire mod and be able to start your bike however you want (including with the clutch engaged and the bike in gear, which makes for an interesting push of the start button)
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post #5 of 21 (permalink) Old 10-02-2017, 12:21 PM
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Found out my bike with the Two-Wire mod, the sidestand switch still works. But it will crank with it in gear and the clutch out. MTB has told me this a couple times, I keep forgetting.

2003-21k mi
Shaved w/UniPK92+Stock Jets-TPE/MOSFET-Shinko Tires-AGM batt-bags-chrome-LEDs...more
__________________________________________________ ____________
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Owner's Manual: http://www.mediafire.com/file/nscb5f...ers+Manual.pdf
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post #6 of 21 (permalink) Old 10-02-2017, 12:24 PM
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That damn start circuit wire running to the CDi ... Wish I knew what function it serves. Good chance the 2-wire mod would help. 50-50 chance?

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

Owner's Manual: http://www.mediafire.com/file/nscb5f...ers+Manual.pdf
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post #7 of 21 (permalink) Old 10-02-2017, 06:06 PM Thread Starter
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The 2 wire did not help at all. I also made sure all the ignition cut-outs were engaged. I am wondering about pin 14 on the JB which is also connects to pin 5 on the CDI. when the bike is off, I get nothing, when the key is on I get about 9.5 volts. Is that normal?

I am beginning to believe it may be the CDI box. I have no idea why the PO stopped using it in 1997. Has anyone taken a CDI apart that we know of?

What is the little box under the flasher relay? It looks like it may be sealed up with epoxy?

Thanks again

Last edited by willyb99; 10-02-2017 at 06:09 PM.
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post #8 of 21 (permalink) Old 10-02-2017, 07:08 PM
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Regarding pin 5 on CDI to 14 on JB, that is the wire the CDI uses to determine if it should prevent spark according to the interlock. When the bike is on, the CDI pushes voltage towards the JB. If the JB provides a path to ground, the bike should run. If there is no path to ground, then the CDI provides no spark. It's possible there's a relay in the CDI using the current on that path as a trigger. I've not seen the insides of one of our CDI boxes. Would love to see pictures of every detail inside.

1992 US-nonCA * tuxedo mod * r/r relocated

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Service Manual Download
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post #9 of 21 (permalink) Old 10-02-2017, 08:25 PM
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Quote:
Originally Posted by Thorn View Post
I've not seen the insides of one of our CDI boxes. Would love to see pictures of every detail inside.
A fuzzy video.

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

Owner's Manual: http://www.mediafire.com/file/nscb5f...ers+Manual.pdf
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post #10 of 21 (permalink) Old 10-02-2017, 10:02 PM
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Geeze, no wonder they cost so much. That's a lot of components crammed on there. Would be a pain to reverse-engineer!

1992 US-nonCA * tuxedo mod * r/r relocated

Vulcan slang for newcomers
Service Manual Download
Wiring Diagram + annotations * still undergoing revisions, but still more useful than the generic one. Let me know if you find mistakes or think something additional should be added
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