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Old 09-20-2011, 08:43 PM
Countrymans.com's Avatar
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Coil problem or what??

Hi all:
I have a 2002 Magnum 500 RMK and am wondering what are the symptoms of a failing coil. It runs about 10 minutes then starts to dog out bad. Has anyone ever had the coil fail? Do they ever fail when they get hot? The problem seems to maybe be heat related as it runs fine until it warms up good. Do they usually go out completely all at once or do they slowly die and act up over time? Can you test the coil to see if it's good? If so what are the specs for it? And what about the stator? Do they usually simply go tits up or act up over time? What are the symptoms of them failing? I have worked on lots of machines and this thing is the hardest to diagnose of them all. Or could it be the CDI? God I am totally at a loss here. Someone help me out ok? Thanks.

PS I already had the carb rebuilt and replaced the fuel pump and all the lines too. So I assume it's not the fuel system but who knows for sure.

Last edited by Countrymans.com; 09-20-2011 at 10:53 PM.
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Old 09-21-2011, 08:09 PM
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They do fail. Sometimes all at once and other times a little more each time. Heat related failures tend to be progressive based on temperature. Testing a coils resistance on the primary and secondary windings is the way to go initially, get yourself a manual that gives the specs or contact your local dealer. Test it cold and again when hot.

Any other repair history?
What condition is the spark plug in? Replaced when?
Gets better when it cools off?
What is the battery voltage, stopped, idling and at 2500 rpm? Condition and age of battery?
Is the fuel tank vent clogged or pinched shut?
Fuel filter?
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Old 09-21-2011, 08:22 PM
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HI.sounds like you have your hands full!I have had coils behave that way in some cars.I would assume it would be the same in your case.Yes, you can test them with a meter and in most cases rebuild them.according to my manual the CDI is is at fault only after everything else has been ruled out.I suggest you buy a manual because it covers all of that plus has the specs.Im not an expert,but I hope that helps
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Old 09-21-2011, 08:37 PM
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My book says
Ignition Coil primary resistance ---------------------- 0.3 to 0.5 Ohms
Ignition Coil secondary resistance
w/Spark plug cap installed -------------------------- 10,400 Ohms
w/spark plug cap removed -------------------------- 5,400 Ohms
Spark plug cap resistance --------------------------- 5,000 Ohms

Hope this helps, Buddy
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Old 09-21-2011, 10:40 PM
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Hi again:
Can you test the coil on the machine? Which wire is for the primary and secondary? I mean what color? One more question. On the polaris site it shows the coil and the spark plug wire as being separate. Does the spark plug cap detach at the coil or does it detach on the end of the plug wire? On the polaris site it looks like at the end of the plug wire not at the coil. I just wonder if maybe the spark plug wire has been pulled out somewhat making it not spark right. Is the coil more likely to be the culprit or the stator? I mean how reliable are these stators? I seem to see a lot of people have them fail and the polaris mechanic said sometimes the stator goes out when they get hot. Anyone have to replace the stator? I know they are expensive too. I found one online for 125. How hard is it to replace it? I guess you would have to remove the pull starter, pull the flywheel, and install it. Are they hard to install? The coil is not too bad at around 35. Thanks.


Now to answer some questions. Brand new plug just installed and gapped. New fuel lines, new fuel pump, and rebuilt carb by a polaris tech (I took if off and took it to him). New fuel filter. New battery. Also new muffler as I thought maybe it might be the problem. No clogs on the gas tank vent. It usually runs perfect for about 10 minutes with a good idle and acceleration. Then suddenly out of the blue it craps out and dies. If I let it set for a few minutes fires right back up and runs again but usually shorter the second time since it is now pretty hot. The coolant level is perfect though. And the radiator fan seems to work right. No crud in the radiator fins either. It really doesn't get that hot just hot enough to make it crap out suddenly. And yes it gets much better when sat for a long time and allowed to completely cool down. I originally thought it must be the carb but am leaning now towards an ignition problem. What do you guys think? Thanks Buddy for the coil stats. Thanks everyone else too.

Last edited by Countrymans.com; 09-21-2011 at 11:05 PM.
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Old 09-22-2011, 04:46 AM
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It seems to me that if the stator was going bad or completely failed, you would have battery charge problems, as the stator (alternator) is what charges and maintains the charge of the battery along with the voltage regulator. I doubt the stator. Likely the coil or CDI.

Are you having any battery problems, had to recharge the battery? Did you check its voltage at idle, off and at higher rpms?

When the engine quits, do you have any spark? weak spark? no spark at all?

The plug wire, mine at least, has a cap/boot at both ends and is able to be removed from the plug and the coil. Check both ends, and apply dielectric grease.
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Old 09-22-2011, 07:34 PM
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Hi Walter:
I really didn't know that the stator was the alternator. I thought it was part of the magneto which generates the spark. The battery is no problem at all. It holds a charge great as far as I can tell. I did notice that the lights seem to dim a little at night when riding. Just for a few seconds though really. Could that be a sign of the stator going bad? As far as when it quits it fires right back up after you sit a few minutes, although once warm it will then start to dog out rather quickly. As far as the coil goes usually the spark plug wire plugs into it but the parts diagram shows only that the cap comes off. I probably need to call Polaris and find out for sure what it does. If the stator was going bad would it cause you to lose spark? Or would it just let your battery run down? The reason I ask is because the polaris tech said sometimes the stator can fail when it gets hot. Does that make any sense to you? And would it then affect the spark? I always thought the spark was timed by the CDI and that the coil was what generated the spark. So if the spark is failing seems to me most likely it's the coil and not the stator (alternator). Do you agree? And exactly how would you test the coil? Could you be specific? Thanks.

Last edited by Countrymans.com; 09-22-2011 at 07:38 PM.
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Old 09-22-2011, 11:13 PM
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I think you are on the right track.
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Old 10-03-2011, 03:22 AM
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Does anyone know where you can get a good cheap replacement coil for my Magnum 500 RMK? Polaris wants 109 bucks. Thanks.
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Old 09-25-2013, 08:41 PM
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Spark

U'r right the CDI does send a timed spark and the coil does generate the spark but the voltage comes from the stator than boosted by the coil and timed by the CDI, the magnito turns around the stator which generates voltage for the battery to charge and also to u'r coil ect.

Quote:
Originally Posted by Countrymans.com View Post
Hi Walter:
I really didn't know that the stator was the alternator. I thought it was part of the magneto which generates the spark. The battery is no problem at all. It holds a charge great as far as I can tell. I did notice that the lights seem to dim a little at night when riding. Just for a few seconds though really. Could that be a sign of the stator going bad? As far as when it quits it fires right back up after you sit a few minutes, although once warm it will then start to dog out rather quickly. As far as the coil goes usually the spark plug wire plugs into it but the parts diagram shows only that the cap comes off. I probably need to call Polaris and find out for sure what it does. If the stator was going bad would it cause you to lose spark? Or would it just let your battery run down? The reason I ask is because the polaris tech said sometimes the stator can fail when it gets hot. Does that make any sense to you? And would it then affect the spark? I always thought the spark was timed by the CDI and that the coil was what generated the spark. So if the spark is failing seems to me most likely it's the coil and not the stator (alternator). Do you agree? And exactly how would you test the coil? Could you be specific? Thanks.
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