A A A A Author Topic: Ignition Coil Ground/Earth?  (Read 243 times)


Ignition Coil Ground/Earth?
« Started on: 23-Aug-18, 13:45 »

I've just removed the two ignition coils which are mounted to the top frame tube of my 82 CX500 Shadow (Transistor Ignition) by a two-piece clamp.  Under the top clamp was a strip of unpainted metal on the top frame tube about 20mm wide, whereas the top clamp is 30mm wide.  Was this strip of bare metal intentionally designed to provide an earth/ground electrical route for the coils, via the clamps?  Testing with the multimeter on the Ohms setting, I can't find any connectivity between the clamp and any other wire.  The wiring diagrams in the Haynes book show the coils connected only by the Blk/W & B wires on the left hand coil, and the Blk/W & Y wires on the right coil, but earlier model schematics show the coils connected to the earth/ground on each, and a P wire from one and a Y from the other, connecting to the CDI unit.

So, my question is:  Can I go ahead and paint over the subject bare metal strip with gloss black like the rest of the frame top tube?

I was thinking that the earlier CDI bikes earthed their coils through this bare metal patch, via a clamp, and either mine is an old frame, or they never got around to informing the paint shop of the changes, but, looking at a CDI model, I see that the coils are directly bolted on to the frame.  So, the subject bare metal strip makes no sense.



Re: Ignition Coil Ground/Earth?
« Reply #1 on: 21-Nov-18, 12:50 »
I've just gone ahead and painted over the bare metal strip on the top-tube, assuming it was a redundant grounding/earthing point, as the wiring schematic shows no indication of such a ground point.  Now I regret that I have compromised an original feature!


Re: Ignition Coil Ground/Earth?
« Reply #2 on: 24-Nov-18, 17:58 »
You've only compromised the original if someone actually takes the coils off.  :grandpa:

Very few bikes are that original if we look deep enough.

Replacing some un-available parts ensures that.

We use aftermarket Cam chains, water pump seals, stators, etc.


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