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Old 05-07-2013, 07:02 AM   #1
thewhistler63 OP
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Location: Jacksonville, FL
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Eh? R100/7 Coil Wiring

While troubleshooting a electrical problem (little or no spark) I chose to eliminate the coils as a possible problem source with 2 new bosch blue coils.

During the operation I lost/miplaced/whatever the jumper wire between the two coils. My solution was to take an old set of points and take that wire (already had one end female spade) and use that.

I used another reference in this forum to get the green/blue wire and black condenser/points wire (hopefully) in the right place.

Since I'm still having spark issues I got to wondering if I should use a thicker gauge wire for the homemade jumper?

Everything was fine until I decided to replace the points.
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Old 05-07-2013, 07:28 AM   #2
oldroadie
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The jumper wire doesn't need to be huge, the amount of current needed to charge the coils is relatively low in the grand scheme of the ignition circuit, a 16 ga. ought to be more than sufficient.

With the ignition on do you have 12v at the coil input? Where is the condenser wired in? Is the ground point for the points solid? Changed your plug wires? Are the new coils 6v?

The coils get their charge from the 12v battery through the points. When the points break the ground contact the field around the coils collapses and discharges through the plug wire. You could have a poor ground at the points, defective plug wires, or maybe a poor source of 12v to the coils. Really not much else to go wrong.

oldroadie screwed with this post 05-07-2013 at 07:34 AM
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Old 05-07-2013, 12:20 PM   #3
190e
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It's important to observe correct polarity on the 6 volt coils as it affects the polarity and therefore strength of the spark.

Rear coil should have +12v feed on terminal 15 and the link wire on terminal 1. front coil should have the link wire on terminal 15 and the points wire on terminal 1. Tacho wire where appropriate also goes to terminal 1
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Old 05-07-2013, 12:36 PM   #4
disston
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A /7 has a left and right coil, not a front and rear. But you know this I think so what am I missing?

What oldroadie said. The blue green wire to the left side coil should have battery voltage. Plug wires and plug caps should check out. New plugs may be needed.
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Old 05-09-2013, 12:22 PM   #5
thewhistler63 OP
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Tried Bosch 6v Blue Coils problems ensued.

I'm getting a blue spark after pulling wire and connecting an extra plug and laying onto cylinder (turning over starter). Also can manipulate points manually to get same spark.

The new bosch coils 6v blue coils from euromotoelectrics are installed. They are a little longer than stock I have them wired as indicated on other messages (blue/green to left coil+, jumper from left- to right +, black (condenser/points) to right -.

I'm still getting a spark by touching a spare plug (new) to the head by turning over starter. Can also open points by hand and get a spark.

However, I don' tknow how to measure current at various points along the route.

The real mystery is Why is the left coil (the one with the green/blue on +) getting so DAMN HOT??? Is it shorting out or DOA (they are new). When first installed I noted after a while of no joy that they were both coming in contact with the tank bolts (since they are longer). Were they possibly not grounded properly.

Lots of stupid questions I'm sorry but any help would be appreciated. For now I'm putting on the old coils which were probably perfectly fine and see what happens.
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Old 05-09-2013, 01:20 PM   #6
disston
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I think I have heard the Blue Coils called Volkswagen Coils? I believe I have heard several of the Gurus say that they won't work but we all know that there are riders using them and apparently have no problems. I think going back to the original coils may fix this.

I have several sets of Blue Coils but have never installed them.
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Old 05-09-2013, 02:19 PM   #7
190e
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Curious that only one coil is getting hot unless it's faulty. I'd measure the primary resistance of the 2 coils and compare them.

Measuring the current is easy enough, just break the circuit at any point and insert an ammeter. You will get different results depending on whether the engine is running or not an at what revs.

I've only done it with the original Bosch black coils but I suspect the blue coils would not be radically different. I think the difference between black and blue coils is in the turns ratio between primary and secondary windings which would not make a big difference to the current draw.

With the engine stopped and the points closed I read approx. 3.5 amps. Arguably it should have been at least 4 amps but there will be some resistance in the wiring and the internal resistance of the ammeter itself will reduce the current a little.

With the engine running the average current falls substantially because of the effects of dwell and the current rise time. I saw approx. 2.4 amps at idle. The accuracy of the figure may change according to the type of ammeter used but it should definitely drop a lot from the static reading.

As you rev the engine the average current falls even further to under 2 amps as there is insufficient time between sparks for the coil to reach saturation.
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Old 05-11-2013, 08:59 PM   #8
Plaka
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Quote:
Originally Posted by thewhistler63 View Post
/snip

Everything was fine until I decided to replace the points.
So why are you fooling with the coils? If everything was great until you changed X, then the greatest likelihood of the source of your problem is X.

An overheateing coil is either defective (internal short) or is shorting somewhere externally. The are not made to have current continually flowing through the primary. Check the coil for internal shorts and then check the circuit for external shorts.

But make sure the points are kosher first.
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