Intermittent Spark - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 14 (permalink) Old 04-14-2016, 03:31 PM Thread Starter
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Intermittent Spark

Still going through the bike and it seems like every step forward is one backward. Replace plugs and started it up, ran fine for a couple of mins then died. Would turn over but not start. Pulled a plug and no spark. Then did the back plug, same thing no spark. Walked away form it for a couple of mins and came back and pulled it out of the garage. Tried it again and same thing started up then died. Pulled plugs again no spark. After reading the forums I started with the kick stand switch. Because I lowered the bike I figured the plunger wasnt going in all the way. Put a piece of metal to between the 2 and it started again. Ran for a couple of mins then died, no spark, readjusted the kickstand got spark, started and ran then died, same pattern. I think I m going to bypass the kickstand however I have a suspicion it is still something else, if this doesnt work what do you think the next option is, Pickup coils, ignitions coils? Thanks for any input, I really appreciate it,

Mark

Last edited by Markak; 04-14-2016 at 03:33 PM.
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post #2 of 14 (permalink) Old 04-14-2016, 03:41 PM
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You can use a meter to verify if there's an issue with the kickstand sensor, but to me it doesn't sound like it. Assuming you're absolutely sure there's no spark, I'd look into testing the pickup coils (and potentially doing the pickup mod to bring them in a little closer). If you're not getting spark on either cylinder, it doesn't sound like the ignition coils are the issue.
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post #3 of 14 (permalink) Old 04-14-2016, 03:47 PM Thread Starter
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Caleb,
Yes I am absolutely sure there was no spark, tested both front and back, then once I readjusted the kick stand it had spark and I put the plug back in and it started up, end up repeating the same pattern 4 times before I had to get back to work but yes Im open togetting all the info I need and I really appreciate it, i swear last year I had zero problems and now its a nightmare,


Mark

Last edited by Markak; 04-14-2016 at 03:51 PM.
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post #4 of 14 (permalink) Old 04-14-2016, 04:23 PM
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Possibly an intermittently bad pickup coil? would explain why the starter has power but both ignition coils lack spark...
When engine warms up, coil craps out? Maybe?
You can check for a change in resistance cold vs hot at the coil connector. See page 274 of the online repair manual.
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post #5 of 14 (permalink) Old 04-14-2016, 04:28 PM Thread Starter
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Thorn,
Either way I am going to do the pick up coil mod and will definitely test the pick up coils prior, thanks Mark
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post #6 of 14 (permalink) Old 04-14-2016, 04:34 PM
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Just throwing this out there. When I got my bike, it started up the first few times okay, but then suddenly died out of no where. It turned out to be no sparks and it was due to corrosion. The bike was so old that the male and female plugs on the ic ignitor was not making a connection . I tested it with a multimeter and didn't even get a reading when I touched the leads to the same pin. Cleaned it off and it finally worked.

You can check to see if the plugs are making a proper connection, and not just a loose one. Or maybe follow the wires and make sure there is no unintentional contact. You can also go through the steps in the manual for verifying that your coils are good.

This is what the manual says: If the side stand is down, the clutch engaged, and the transmission in gear, the ignition system will not work.
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post #7 of 14 (permalink) Old 04-14-2016, 05:11 PM
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Next time you lose spark (assuming you're idling in neutral resting on the side stand), just check to see if your neutral light is working as expected. If it is, then your interlock circuit 100% has a path to ground, and your ignition system is the cause, not the kickstand.
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post #8 of 14 (permalink) Old 04-14-2016, 06:36 PM
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After reading the above suggestions from others....

I'd suggest doing the "clutch switch" mod at the grip end of the handle bar... ( so you can start in gear ).

Follow that by yanking the booted sensor off the kickstand. ( and that's an NC (( normally closed )) switch, so tape off the loosed ends independent instead of shorting them ).

And checking the neutral sensor wire ( green ) that runs down near the belly and ( at least on my machine ) is a single unprotected wire that should be in better housing IMHO.

Any of those three fail, ( as Thorn pointed out ), and bike will just look at you like a mule.


As Caleb mentioned... the odds of both coils being bad at the same time is extremely high. You can test them as well though without yanking them off... They get old with heat and the insulation eventually melts off of them. So failing at the same time would be rare unless your bike had an "event" of excessive heat, or excessive current running through both at the same time, which would be against the nature of the design.

... and if all of those things fail, the next culprit would be the "Ignitor" IC on the back lower right of the battery-cage. I forgot what that's called... but it says "Ignitor" on it. So that's what i call it. And that would need to be replaced since it's unrepairable.

Hope this helps, and i stand corrected in advance.
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post #9 of 14 (permalink) Old 04-15-2016, 08:29 AM Thread Starter
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Thank you guy all the help on this, I really appreciate it. When i bought the bike it was all stripped down (no speedo/tach/turn signals). All the wires were cut and taped. Last year I had zero issues with the bike however the last couple of months its been harder and harder to start. I replaced the plugs with the iridium plugs hoping this would be easier to start. This is a totally new thing that has happened this last week with the spark and no spark deal. Sunday I will test the pick up coils and do the Mod to them either way. I was just hoping since every time I lost spark I missed with the kickstand plunger I got spark back but then again just for it to die and loss spark. I appreciate all the advice and will try everything stated until its fixed. Thanks again for the input as it is really needed,

Mark
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post #10 of 14 (permalink) Old 04-15-2016, 01:35 PM
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Quote:
Originally Posted by Markak View Post
Thank you guy all the help on this, I really appreciate it. When i bought the bike it was all stripped down (no speedo/tach/turn signals). All the wires were cut and taped. Last year I had zero issues with the bike however the last couple of months its been harder and harder to start. I replaced the plugs with the iridium plugs hoping this would be easier to start. This is a totally new thing that has happened this last week with the spark and no spark deal. Sunday I will test the pick up coils and do the Mod to them either way. I was just hoping since every time I lost spark I missed with the kickstand plunger I got spark back but then again just for it to die and loss spark. I appreciate all the advice and will try everything stated until its fixed. Thanks again for the input as it is really needed,

Mark

Now it's starting to sound more like a battery problem which leads to our dear old friend the stator. The stator takes its time to die because just like the ignition coils, its magnet wire with thin insulation that melts slowly due to heat. Because of that, it will charge the battery less and less over time as more and more of its coils short together.

This leads the troubleshooter to believe at first that the battery is ok. "Hey i just put in a brand new one! Ran great first day!". And the bike will crank the starter motor to some degree but no spark will be "hot enough" to jump the gap of the plug while the starter is turning and sucking juice. After the bike gets going again, it charges insufficient, but warms up and the troubleshooter is led to believe it was just cold. So sure enough, when it gets to sit overnight again, it will certainly be cold in the morning.

Checking the stator is an easy process that involves removing only three wires from their plugs and the three wires can be put back together connected in any order. You'll need a voltmeter that can handle upwards of 120VAC (like wall current ), DC voltage with a nice 24V scale if its analog ( other higher will do, but be harder to read ), and be able to measure resistance. It doesn't need to be expensive, but i'd suggest a digital meter. The meter does not need to be super-accurate like a bench meter, but it does need to be sensitive enough to read battery voltages between 10.5 and 15 because an automotive battery that is only 12v may as well be dead and there is a big difference between 12.5 volts and 13.5 volts, only the latter will kick the rectifier enough to start charging the battery with enough juice to make any difference.

Checking the stator ONE TIME can be compared to checking the oil one time. To really know if it truly is the stator you'll need to check it as a regular part of your maintenance routine; only then can you "watch it die" if it starts to fail. Read the Vulcan Verses under the electrical forum about the steps to check the stator.

Hope this helps and i stand corrected in advance.

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