Vintage BMW Motorcycle Owners

Hi- my1958 r69 has been in storage for 12 years following it being damaged at a show. I decided it was time to get it back functioning. All has gone well with replacing damaged handlebars, bent saddle, crushed headlamp. I tried to start it, but no spark. I have so far replaced Ignition coil, condenser(capacitor), points, HT leads, spark plugs and caps. I have checked the timing. I isolated #2 from headlamp switch to coil so no ground connection. All to no avail. I really do not know what to do next! Any help from any magneto guru's would be much appreciated. From a very frustrated biker in The New Forest, Hampshire, England.

Hi
copy and paste your post to:
Vintage (1948-1969) Motorcycle Section
Tommy

I will see if I can move the thread.

Are you familiar with the magneto safety gap? The two HT leads connect to the coil and just below this connection point are two points, one for each lead. The gap is supposed to be 10-11mm. If too close, the spark energy will jump to the points and not go to the spark plug.

Yes, I checked and adjusted the safety gap to 10.00- 11.00mm once I fitted the new coil.

Was the magneto aligned properly? If it wasn't, then it's possible there wouldn't enough energy to create a spark.

I don’t have much to add to what the others have said. However, I had a similar situation and it turns out the new condenser I put in was bad. Swapped it for another and the bike started right up.

schrader7032 wrote: ↑

Sat May 14, 2022 5:42 pm

Was the magneto aligned properly? If it wasn't, then it's possible there wouldn't enough energy to create a spark.

This is where I got confused- when the"v" mark is in line with the line on the rotor, it aligns with a red painted dot on the flywheel, viewed through the inspection hole, not where the"S" mark is on the flywheel. If I move the flywheel so the "S" mark is dead centre of the inspection hole the line on the rotor is way to the right of the "v" mark. Which is the correct way?

The line on the magneto disk should be in the "v" in the magneto body when the S-mark is in the middle of the timing window. I'm not sure what the red mark represents. That must have been placed there by someone in the past. There are three marks on the flywheel, mostly they're painted white - OT (or top dead center), S, and F for full advance.

As I think about this, though, I'm not sure a misaligned magneto rotor would cause a no spark situation. The magneto needs to be aligned so that when the magneto outputs the maximum spark energy, the engine is near the S-mark. The magneto spark is actually pretty weak at slow RPMs such as kicking speed, so this timing needs to be the best in order to get the bike started. If the magneto were aligned somewhere else, seems like it would still spark but just at the wrong time.

Thank you so much for your response. I was also thinking that I would still get a spark, but just not at the right time as the set-up is at the moment. When i tested with a voltmeter between the primary winding on the coil and earth when I kick over the bike, 6v is disayed twice during the kick. Likewise when I tested on the secondary winding ( ht lead to spark plug) it read the same on the voltmeter. Is it possible the magneto has lost its magnetism, and not producing enough voltage.