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Offline XC204

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Coil?
« on: August 31, 2012, 10:22:55 AM »
On my CB500 1973 I can measure 4.5 ohms on the low side seems ok. I try to measure to Hi voltage side  to black/white wire it should be around 15k correct I get an open, both coils act the same. I do get 13.5 k plug lead to plug lead. these are off the bike and on the bench . Am I missing something stupid?
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Offline Round Dice

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Re: Coil?
« Reply #1 on: August 31, 2012, 10:53:18 AM »
I don't know if I understand your question but it doesn't sound like anything is wrong. 

A coil should have one wire that is blue or yellow, one wire that is black and white, and two plug wires.

The two plug wires are connected.

The blue (or yellow) wire and the blk/wh wire are connected. 

The plug and the blk/wh wire should not be connected. 

Are you not getting a spark?
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Offline Rigid

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Re: Coil?
« Reply #2 on: August 31, 2012, 11:33:14 AM »
Often a no spark issue is the points.  Are they clean and adjusted?  If it is misfiring and sparking at the points, it is a failed condenser.  I do bench test coils from time to time but like most things, the proof of their function is installed and under load.
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36 years of this stuff, here to help.

Offline TwoTired

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Re: Coil?
« Reply #3 on: August 31, 2012, 12:43:48 PM »
Quote from: XC204 on August 31, 2012, 10:22:55 AM
On my CB500 1973 I can measure 4.5 ohms on the low side seems ok. I try to measure to Hi voltage side  to black/white wire it should be around 15k correct I get an open, both coils act the same. I do get 13.5 k plug lead to plug lead. these are off the bike and on the bench . Am I missing something stupid?
There should be no continuity between low side and high side.  The electrical coupling is by electro-magnetics rather than conduction.
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Offline XC204

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Re: Coil?
« Reply #4 on: August 31, 2012, 04:01:24 PM »
In an auto coil the Hv and low side are on the same core but the coil ends low and hi are tied together as they go to the points I believe. In an auto transformer config if I remember from school. One side of the Hv should have a reference to ground so the spark can jump to it I'm really confused now . The coils are off the bike on the bench wires were cracked and very loose so I thought I'd do some continuity checking. Any one have a diagram of the dual coil internals?
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Offline XC204

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Re: Coil?
« Reply #5 on: August 31, 2012, 04:06:19 PM »
What a DSh.. I am ,looked at manual ,didn't think it would show internal wiring of the coil. Sorry I'm my own worst enemy!
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