Intermittent Spark on 2004 AC 400 4x4 auto
 

Well, after hours of working on my friends atv (cleaning carb 3X, adjusting valves 2X, tracing wiring looking for shorts, replaced the battery twice) I finally figured out that the reason it is so hard to start is that it only fires every once in a while. It will crank and crank and then fire once or twice and then crank some more with no spark and then fire a couple more times(inline spark tester is a cool toy). If I get it to start, it will stay running as long as the idle is set high.
Any suggestions what might cause this? Searching through threads on this forum, I'm sort of leaning towards pickup coil.
What is the test procedure for this and how do I access it to replace it?

Well, after more searching I am starting to believe the flywheel probably has flung the magnets. Going to pull it apart tonight.
Is there anyone in the St. Louis area with a flywheel puller?

Thanks to these forums, I have saved a lot of money troubleshooting.

The flywheel is definately in pieces. There isn't a single magnet that isn't chipped up and laying in pieces. It explains a lot actually. There were a couple times that I had it in Neutral and it wouldn't roll (magnet between the gears). A few times I would be cranking and it would act like it was locked up (thought it was the starter).

Several guys have pposted here recently about difficulties with the magnets on their flywheels. One glued the loose magnets back on and had luck with that.

I am wondering if the high amount of heat generated from the engine is effecting the glue on the magnets? OR is it just a defect on some machines?

SJ

I had the same problem with one I was working on. Some have gotten AC to warranty the flywheel. An Eiger flywheel is the same and about $40 less than AC. The updated flywheel has the magnets enclosed also.

I just went through the exact same troubleshooting -valves. Pulled cover off and found only 2 magnets on the flywheel. the others were stuck to the stator. Only 755 miles. I had the dealer check with Arctic Cat and Cat is going to cover the part. Labor only for me. Heck the thing is already apart, LOL!