Kawa FC420V coil air gap


Old 07-15-10, 05:13 AM
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Kawa FC420V coil air gap

I have a John Deere LX176 with a Kawasaki FC420V-ES10. My engine manual, and the posts in the forum, indicate a separate coil and igniter. My Deere only has the coil, which I understand has the igniter built into it. Question is, do I set the air gap the same (.012), and is there a test procedure (ohms) for this coil?
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Old 07-16-10, 01:17 AM
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Yep, set it at that gap. I think there is an ohms test for the coil, but the definitive test would be use a good spark plug, ground it to the engine, unplug the kill wire from the coil, crank the engine. If it doesn't spark, the coil is bad.
Old 07-16-10, 08:07 AM
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Thank you, Cheese. The engine had become hard to start when hot, then occasionally hard starting when cold. Yesterday it would not start at all, but UPS also had delivered the new coil. Set the gap as you said, and problem solved. I tested the good and bad coils using the manual limits for the igniter/separate coil. Limits were 10-.9 to 16.3 kohms New was at 14.8 k, old at 18.6 k. I was expecting much higher resistance on the old, near open circuit.
Old 07-16-10, 12:28 PM
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Unfortunately testing the resistance isn't always a good indication of a coil's condition. Temperature and vibrations both play a role here too. A coil may work fine cold but may have an intermittent problem when warm (when everything has expanded ever so slightly).

Now that I think of it, I don't think any of the very few bad coils I've seen before (I don't work on engines every day) ever tested bad with a meter.

- Joe

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