Diagnosing 1987 KDX 200 Electrical

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aj797
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Diagnosing 1987 KDX 200 Electrical

Post by aj797 »

Bought a rebuilt bike, all electrical was off the bike. Flywheel magnet broke off and wiped out the ignition coil on the stator. I used to work for a motorsports electrics manufacturer and they put a new coil on the stator for me to try out. Flywheel magnet was cemented in place by previous owner. Put everything together, no spark. Kick starting outputs about 20v from either cdi, and .3v from the lightning coil. There is continuity in the spark coil, tested it using a car battery charger and tapping leads, produces no spark. The primary spark coil says on my manual to require 7.2k ohms, tested it to be about 11.4k ohms. Kick starting produces no voltage to spark plug cap, and about 14v with the lead that squishes on top the ground pole disconnected. (tested from the cdi connection to spark plug cap) Not sure what the issue could be, any help would be appreciated before I start buying parts.
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kawagumby
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Diagnosing 1987 KDX 200 Electrical

Post by kawagumby »

regardless of anything else, the ignition coil should produce spark if you run current through the primary side and cut it off. Those coils sometimes lose ground at the grounding side tab of the primary coil. I checked a known good 87 coil and the resistance is 0.16 ohm across the primary coil (checked with two different meters to make sure), the secondary (spark plug side) reads 6.5 K ohms. Hope that helps.

My factory manual states the primary side resistance should be .22 ohms +/- 20%
secondary side should be 7.2 K ohms +/- 20 %
1994 KDX200, Beta 200rr, yz125, yz250, kx100 modded for adult, gasgas contact 250.
aj797
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Re: Diagnosing 1987 KDX 200 Electrical

Post by aj797 »

Thanks it does, I think just buying a new coil is the way to go for step 1.
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