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Jeff Policky
Jeff Policky, Motorcycle Mechanic
Category: Motorcycle
Satisfied Customers: 2425
Experience:  Yamaha Gold, Suzuki Gold, Honda Bronze, Polaris Bronze, BRP
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I read the info you posted on the 2002 400ex with no spark.

Customer Question

Hello I read the info you posted on the 2002 400ex with no spark. I also have the same model and year with no spark. I have a coil transformer and have fired the coil. I tested the blue/yel wire and have 245 ohms . The blk/w wire is open when key is on. So my question is when I have 55 less ohms om
JA: Thanks. Can you give me any more details about your issue?
Customer: Sorry bumped the screen. Less than 300 ohms is it bad ?
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Submitted: 1 year ago.
Category: Motorcycle
Expert:  Eric replied 1 year ago.

Hello,

Its pretty hard to say if that ohms reading is indicating a bad coil. An obvious bad reading would be an open or extremely high or low reading. Your pretty close to the 300 ohm mark so I wouldn't look to that as an issue as of yet. When you test the blue/yellow wire, are you checking that at the ignition coil or the harness coming out of the engine? I would be interested in the ohms reading you get at the blue/yellow wire coming out of the engine. That is the pulser coil. Should be that and a green wire. Unplug those and test between that blue/yellow wire and ground. Any reading with that? Then check between that blue/yellow wire and the green wire. What reading do you get with that?

Customer: replied 1 year ago.
I pulled the plug off at the CDI module and test from there. I tested between the two wires like you suggested and the ohms are the same . Is there a known value for the other wires. I think those have another winding that charges the cdi capacitors that fire the coil. Ken
Expert:  Eric replied 1 year ago.

what about the reading between that blue/yellow wire and battery or engine case ground?