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Discussion Starter #1
Hey all. My bike seems to like fouling plugs, which pisses me off. Also, I've got some kind of electromagnetic interference on the bike which prevents my Veypor speedo sensor from working correctly, which is also a big irritation. Both issues point to a potential problem with the ignition system, so tomorrow I'm going to spend some time looking at coils and so forth.

Looking at the manual, they show a procedure for measuring voltage from the coils and from the signal generator, but both tests require the use of a "peak volt adaptor". My guess is that this is basically just an RC circuit or something that charges a capacitor and discharges it through a resistor, but that's just a guess and probably not relevant to anything. :)

My questions are:

1) What is this PVA thing, and where can I get one?

2) Is there a DIY alternative to the PVA?

3) If the coils and stator pass the resistance tests, then how confident can I be that the ignition system is OK? In other words, how important is the voltage testing? To me it seems pretty important.

4) Is there a spec or procedure for testing the spark plug wires? Normally you'd test resistance and do a visual inspection for cracks and/or spray the wires with water while the engine is running - maybe with the integral coil/wire setup you can't do a resistance test? I can still do the others.


Any advice or info much appreciated.
 

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You can tell a lot about the spark voltage by just looking at, and listening to, it. Stick a thin screwdriver in the spark plug boot and hold it near a ground and start cranking. Once it starts sparking move the screwdriver farther and farther away from the ground and see how long of a spark you can get. It shoud be more blueish and not yellowish and making a cracking sound (like a taser :))

The signal generator is telling it when to spark and if there was a problem with that the motor would miss fire.

I would think the carbs are causing the plug fouling. A weak spark is going to cause it to run bad before fouling the plugs. Don't know what's up with the speedo. Maybe a bad regulator/rectifer could cause a problem.
 

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Discussion Starter #3
You can tell a lot about the spark voltage by just looking at, and listening to, it. Stick a thin screwdriver in the spark plug boot and hold it near a ground and start cranking. Once it starts sparking move the screwdriver farther and farther away from the ground and see how long of a spark you can get. It shoud be more blueish and not yellowish and making a cracking sound (like a taser :))
Thanks. I did something like this back in the summer and I thought it looked a bit weak, but I don't know how long of an arc it should be able to throw. What should I be looking for? 2mm? 3mm? 5mm?

The signal generator is telling it when to spark and if there was a problem with that the motor would miss fire.
I think that the signal generator on the SV actually works as a magneto, too (I could be wrong) - so it's providing the spark energy, not just the timing. That would explain why there's a test for the voltage out from it.

I would think the carbs are causing the plug fouling. A weak spark is going to cause it to run bad before fouling the plugs. Don't know what's up with the speedo. Maybe a bad regulator/rectifer could cause a problem.
A bad R/R can cause the problem, and did. So I replaced it with an aftermarket unit and the speedo and R/R worked fine for a year or so. Then my R/R went bad and killed 2 headlights and a battery so it was replaced again under warranty by the aftermarket R/R folks, but the speedo stopped working. I had changed from the OEM sensor to the Veypor-supplied sensor at that time (since I did a front end swap), so I assumed it was related to the routing of sensor wiring or something like that.

The 2nd new R/R went bad when I was on a trip, 1000 miles from home, and very ****** off. It has since been replaced with what appears to be a very nice and reliable unit for a 600RR bought new from a Honda dealer, and my charging and voltage probs are gone, but the speedo still doesn't work. Diagnosing it using my Pro-Oiler I can see hundreds of spurious odo ticks with the bike sitting stationary with the engine running.

I sent the Veypor back to customer service to have it inspected and they said it checks out fine. I'm afraid to put it back on because I'm sure it's going to still not work and I feel like I'm out of options with this f'n thing.
 

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I've never looked at a sv spark but 10mm would be good and 3mm bad. Bad spark makes for hard starting.

The signal generator only supplies a small voltage signal to the ignitor that's only used to tell it where the crankshaft is positioned.

All the spark energy comes from the 12 volts connected to one side (+) of both coils. The neg side goes to the ignitor. The transisors in the ignitor opens the neg connection, at the right time, which stops the flow power through the coils, collapes the magnetic field, and makes the plug spark.

If you blew out headlights, then there was high voltage going through your bikes whole electrical system. I'm not sure how a Veypor can handle that.

Why don't you lift the front wheel off the ground, turn on the ignition but don't start it, spin the wheel and see if the speedo works.
 

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Discussion Starter #5
I've never looked at a sv spark but 10mm would be good and 3mm bad. Bad spark makes for hard starting.
Great, thanks.

The signal generator only supplies a small voltage signal to the ignitor that's only used to tell it where the crankshaft is positioned.
Right - I looked at the diagram again and clearly this is how it works. My mistake. :)

If you blew out headlights, then there was high voltage going through your bikes whole electrical system. I'm not sure how a Veypor can handle that.
It's supposedly OK up to 20V, but I thought the same thing - which is why I sent it back for repairs, but they said it checks out OK.

Why don't you lift the front wheel off the ground, turn on the ignition but don't start it, spin the wheel and see if the speedo works.
I did that - the speedo sensor correctly detects the wheel turns. I had a Pro-Oiler wired to the same sensor which has a diagnostic mode that actually counts the pulses from the sensor, so it's very easy to see what's going on. When the bike is started up, the counter on the Pro-Oiler goes nuts, it's obviously counting plug fires, not wheel rotations.

My next test is to take power for the Veypor & Pro-Oiler from a separate battery, so only the tach signal line will come from the SV. If it works correctly that way, then the issue is noisy power. If it still picks up spurious pulses, then the issue is EMI.


Thanks again for the info and the willingness to help diagnose.
 

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Discussion Starter #6
The coils tested out fine - they were both right in spec for resistance (4.8-5.0 ohms primary, 25 kohms secondary), and when I did the spark gap jump test described by Marc, I got a solid 10-11mm jump for the rear coil, and ~8mm for the front.
 
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