R69S with no spark

My R69S suddenly died while riding. I pulled the spark plugs and found no spark. Since then I've pulled off the front engine cover and installed a new condenser. I bypassed the ignition switch by disconnecting the earthing lead to the magneto (Brown and Black wire to terminal 2) and still no spark. Not sure where to go from here. Any ideas?

I'm not near my diagrams for the R69S, so I don't know the wires you're describing. What does the resistance of the coil read? You can read from cap to cap. Have you looked at the safety gaps by the magneto? Not sure why they would change, but there should be a 10-11mm gap there. If for some reason the gap closed up a lot, the path of least resistance would be via the safety gap and not to the spark plugs.

Are you points even opening or closing? If they're not functioning properly, you will get no spark. Could be that the rubbing block on the points failed or rubbed off sufficiently that the points don't even open.

20774 said:

I'm not near my diagrams for the R69S, so I don't know the wires you're describing. What does the resistance of the coil read? You can read from cap to cap. Have you looked at the safety gaps by the magneto? Not sure why they would change, but there should be a 10-11mm gap there. If for some reason the gap closed up a lot, the path of least resistance would be via the safety gap and not to the spark plugs.

Are you points even opening or closing? If they're not functioning properly, you will get no spark. Could be that the rubbing block on the points failed or rubbed off sufficiently that the points don't even open.

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The points appear to be working properly, and the problem doesn't appear to be the ignition switch (as stated previously). I suspect that the problem is with the coil and/or the magneto (the engine quit at speed), but I don't know how to test either.

Is the original coil kinda squishy? That's what happens when they go bad...usually the problem is it's hard to start when the engine is hot.

Do you have a multimeter? You should measure the resistance (ohms) from one spark plug cap to the other cap. The reading should be in the 17K ohms range.

I thought I had this problem with my coil, so I bought an aftermarket solid state coil from Vech. It's the Emerald Isle coil. It's form/fit/function and fits in the place of the original coil.

The coil feels firm and I got a 15k ohm reading between the two spark plug lead terminals and 0 ohms between the points lead and the ground lead. So, my guess is the coil is OK. Magneto? How to test that?

My R 69S is sparkless also

But I have a whole different list of issues with it as well. Make sure you have good spark plugs, plug cables and caps. Check and make sure the set screws for the spark plug cables are nice and tight. Then go back and make sure all you electrical connections are tight and free of corrosion. You have to double and triple check the circuit board connections inside the headlight bucket and make sure the key switch contacts in there are clean and function as they should.

Now about my "no spark" issue:I will have to get a few more pictures of the troubled one and start a new thread as this bike has a multitude of issues. Background: Barn find late '69, dismantled in '75, box of small parts tossed, all fluids drained prior to dismantle and that is just the obvious stuff prior to my saving the bike from the scrap pile.

More to come so stay tuned.

You'll need to confirm that 6v is getting to the points, and that the points open and close, thus interrupting the flow of current to the coil. If all that is OK, then it comes down to something wrong with the coil, plug wires, or plugs. You can try new plug wires and plugs. It shouldn't be difficult to swap in a known-good coil, but you would need one to start with.

Have you read this article:

http://www.snafu.org/restore/uandm_bmw_v1.pdf

See what they say about checking for no spark. The system is pretty simple. 6v feed to the points which flows to the coil and saturates it. When the points open, the coil field collapses and high energy is sent out to the plug where it jumps the gap, thus getting a spark. Sounds like some part of that path is not working.

Well, I was stumped. I had originally guessed it was the condenser and replaced that with no result. I couldn't find anything else wrong (checked all the things suggested, points, plug wires, coil, ground wire, etc., etc.). So I gave up for awhile and let a few cobwebs accumulate around the bike. Yesterday I decided to try again with another condenser, and what do you know the bike had spark. I had replaced the original blown condenser with a defective one.

Thanks for the update!