Vintage BMW Motorcycle Owners

Either your points wire is grounding out and not insulated properly OR your headlight switch wire is grounded. Take off the wire to the coil from the harness and see if it sparks. Also NON resistor wires are needed for spark plugs,are yours copper?

>I assume they should open near the S mark?

There should be a horizontal scribe line immediately above the letter S (older bikes had a small ball bearing, hard to miss)--it is this line which should be aligned with the small cut-out on the left side of the inspection hole (looking square into the hole), when the magneto mark is exactly aligned with the v-notch. Getting these spot on helps with kick-starting the bike (the lowest engine speed, and therefore the weakest spark).

Have you tried it with no plugs, and seeing if the coil jumps a spark across the safety gaps? Supposed to be 10mm gap, I believe.

If you're getting spark there, that would leave only the plug wire/cap/plug as culprits. If it doesn't even spark at the safety gap (with open plug caps), then the coil or the magneto rotor? But you state you have pretty much replaced all of these items at one time or another. You removed the #2 connection (gnd) at the switch plate--did you confirm at the other end (the magneto end) that it isn't shorted to ground somehow (independently of the key in/out), i.e. the wire itself is shorted to ground?

I've certainly had frustrating issues before, but this one would have me swearing out loud at the bike! I usually take a few days away from the struggle and try to come back at it fresh. Also, I try to limit it to one thing (one change) at a time, just to avoid any compounding mistakes. Although I must say, sounds like a pretty thorough investigation to me so far. Good luck!

To have no spark at all, as if the ignition switch was in off position, makes me think I am grounding to earth somewhere other than the connection 2 wire from the ignition switch, as I have disconnected the wire from the coil. Is there anywhere else that might create a path to ground out the ignition system?

Points wire insulation/connection and condensor.

Have you put an ohmmeter on the #2 connection point of the coil, and checked for continuity to ground? Since you removed the wire at the coil, rather than in the headlight board, it doesn't (shouldn't) matter if the key is in or out.

If it is open circuit (which is what you want), your coil is (likely) okay. Did you replace the original coil because you knew it was problematic (hard starts when hot), or did you shotgun it as part of this whole repair activity?

What about continuity from the points to the coil? An open circuit there means the points closing doesn't collapse the field and no spark is produced. If the magnetized rotor is moving past the coil, a current is being generated. Take a good look at the other repairs you did, and see if it is possible that one of those actions somehow is contributing to the problem.

Frustrating for sure.

A question on the Emerald Island coils- the additional earth (ground connection ). I have connected this to the right side(viewed from front ) coil retaining screw. Is this ok, or should it be elsewhere?

Don't know if this helps, but here's a couple of pictures of my coil installed. It's been so long, I don't remember what I did with the ground wires.

I can see your wire from the condenser connecting to the top of the breaker points, but where does the orange( might be brown) wire that is connected to the primary(left side of coil viewed from the front) go to? Mine is connected with condenser wire on the top of the breaker points.

This is my set up.

andybee65 wrote: ↑

Sat May 21, 2022 3:39 am

A question on the Emerald Island coils- the additional earth (ground connection ). I have connected this to the right side(viewed from front ) coil retaining screw. Is this ok, or should it be elsewhere?

Ok