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Old 10-15-2010, 12:12 PM   #1 (permalink)
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88' Indy 400 weak spark issue

I'm hoping you tech guys can help me.
(I did some searching but could only find this issue discussed on sleds like the tripples with seperate ign coils.)

I started my 88' Polaris Indy 400 up to put it away last year on a 50 degree day (it's jetted for 30 & colder) with zero issues, walked away from it & left it idling for a couple minutes to warm up. After those couple minutes it stalled.

Thinking nothing of it (figured it was just running rich since it was so warm), I went over to restart it. After trying new plugs, some ether, and breaking the pull cord - I never got it to even try to fire and could not see any spark getting to the plugs when grounded to the head (while pulling it so I wasn't exactly close to the plugs) - so I put it away for the summer & said the heck with it.


Now I'm trying to get it running again.

The FUJI twins have a CDI with integrated coil from what I've read, my original CDI looked like crud, & at the time it stalled I couldn't see any spark while pulling, so I bought another CDI used - this one turned out to be the wrong mounting and plug, but the wires were all the same colors so I wired in the plug off the old one so I could at least test it.

After fixing the pull starter last night I tried starting it with the "new" CDI unit - it still didn't start even with ether. So I had my Fiance watch the grounded plugs as I pulled it over. She said she could see a tiny blue spark on both plugs - after having her pull it so I could confirm this I went back to the book.

Using the books specs I tested the exciter coil, pulser coil and connections and all those resistances seemed to spec out correct or very close anyway (my anolog meter doesn't read super accurately)

So my questions are ;
- did Polaris ever change those wire colors routing, meaning I could have the CDI wired incorrectly onto the original plug?
- what could cause the CDI to not put out enough spark?
- could the flywheel magnets all of a sudden go weak?
- could the exciter/pulser coils spec out right but still not put out enough voltage to fill the capacitor for maximum spark & can you test that?
- could the spark plug wire "caps" have both failed at the same time restricting spark to both plugs?
- could my voltage regulator have failed causing a lack of CDI input voltage & if so where is it (I had assumed the voltage regulator was only related to the lighting coil circuit)?
- is there a possible failed link in this system I'm missing?
- any other ideas?


Thanks in advance.

Jason
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Old 10-15-2010, 02:27 PM   #2 (permalink)
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Did you try new plugs, often fouled ones will not fire sufficiently to work right.
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Old 10-15-2010, 02:28 PM   #3 (permalink)
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Hmm, maybe unscrew the plug caps and cut the wire a quarter inch back and reinstall the caps.
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Old 10-15-2010, 02:49 PM   #4 (permalink)
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Quote:
Originally Posted by RJ Gleason View Post
Did you try new plugs, often fouled ones will not fire sufficiently to work right.
Tried that one in the begining with not only a fresh new set, but even an additional known good set & currently have the fresh new set installed while testing.

Quote:
Originally Posted by YamahaSS440 View Post
Hmm, maybe unscrew the plug caps and cut the wire a quarter inch back and reinstall the caps.
Kinda did that already since I swapped the original caps over onto the "new" CDI when I installed it
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Old 10-15-2010, 04:07 PM   #5 (permalink)
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According to the wiring schematic I just found in the "How to" section - all I need for this system to work is ground to the white wire, voltage & switching voltage to the brown/white & black/red wires and the plugs with a good ground.


Everything else is either lighting/power voltage or shutdown grounds.


That's extremely helpfull. List I know I have a limited list.

I wonder if I could apply a constant battery 12v to the exciter coil side of the CDI to eliminate that circuit as an issue?

Is it possible I should not have resistor caps on the plugs? The schematic shows direct connections & I'd swear the ones on my sled look like resistor caps. I'll check for continuity tonight.
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1996 Polaris Indy 500 - sold
01' XC 700 SP - YeeHaw!!!
01' XC 500 - currently having a couple issues.
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Old 10-17-2010, 09:12 AM   #6 (permalink)
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No one have any idea what the output voltage of those two coils is supposed to be? Or am I barking up the wrong tree following that thought process?
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01' XC 700 SP - YeeHaw!!!
01' XC 500 - currently having a couple issues.
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Old 10-17-2010, 05:44 PM   #7 (permalink)
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Quote:
Originally Posted by gonecheenin View Post
According to the wiring schematic I just found in the "How to" section - all I need for this system to work is ground to the white wire, voltage & switching voltage to the brown/white & black/red wires and the plugs with a good ground.


Everything else is either lighting/power voltage or shutdown grounds.


That's extremely helpfull. List I know I have a limited list.

I wonder if I could apply a constant battery 12v to the exciter coil side of the CDI to eliminate that circuit as an issue?

Is it possible I should not have resistor caps on the plugs? The schematic shows direct connections & I'd swear the ones on my sled look like resistor caps. I'll check for continuity tonight.

do NOT apply 12v D/C to anything!!!

The magneto coils generate A/C voltages.

Go back to your original CDI. The CDI box is specific to the engine and the timing curve is built into it. If you are using the wrong CDI there is a possibility the timing curve is incorrect and could possibly cause engine damage.

Disconnect the single blk. wire at the CDI which will isolate it from the kill circuit in the rest of the sled. See if that has any effect in the off chance there is either a short in the harness or a defective switch in the circuit.

Test your spark plug caps individually with an ohmmeter. Specified impedence is between 3.7 and 6.3 K. If you get readings outside these numbers replace them as they are very inexpensive.

The way you say the engine was running and then quit seems odd ........
I would not overlook the basics , test compression, also remove the carbs and while slowly rotating the engine by hand have a look at the pistons to make sure you see no damage there.

Last edited by mrholmquist; 10-17-2010 at 06:00 PM.
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Old 10-17-2010, 05:52 PM   #8 (permalink)
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Quote:
Originally Posted by gonecheenin View Post
No one have any idea what the output voltage of those two coils is supposed to be? Or am I barking up the wrong tree following that thought process?
There is no published spec for the output voltage of these coils because it is dependant on RPM. You would end up getting a different reading each time you pulled the cord. Also things happen pretty fast and different digital voltmeters may register different values depending on the sampling rates of said meters. I have tried to test the A/C voltage of both of those coils b4 by pulling the cord. My meter gave me around 90VAC on one and maybe 40VAC
on the other. As I said your meter may tell you something quite different but if you are registering a voltage at all on the A/C scale that would tend to tell you the magneto coils would seem to be functioning.
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Old 02-14-2011, 02:48 PM   #9 (permalink)
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The new CDI fixed it, and I installed new plug caps just for good measure.


Thanks!
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1996 Polaris Indy 500 - sold
01' XC 700 SP - YeeHaw!!!
01' XC 500 - currently having a couple issues.
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