Forum bmwbike.com

Dear friends,
the facts are these:
difficulties in starting a hot R50; first , I
checked the fuel sistem : everything's ok (chocolat spark plugs) , put on a new couple of sparks plugs. No resistor spark plug caps on it. ; the advance is setted like Vech teaches.... so I checked the sparks : very, very weak ! quite invisible in the daylight , only visible in the dark of the garage.
So I changed the magneto coil (with a new one called Emerald Island) , and the bike starts , not the first kick, but starts.
Checked the spark again and they are still weak. Could this depends on points and condensor ?



I have no more ideas . Please suggest.

Michele

Hello Michele,
I think there are two possible faults. First check the condensor. It might have a short-circuit when the engine and the condensor as well is warm.
The other possibility is to check the correct ignition setup-up. The BMW twins with magneto ignition are very sensitive in this way.
When you need some more informations send me a e-mail!

So long!
Frank

Maybe the spark is not supposed to look strong in bright daylight. And often a hot bike cannot be expected to start on the first kick.
I have never seen a spark except in shade or in a garage. And my bike has a perfect rewound Huggett coil but often takes 2-3 kicks to start when hot, due to carburation and technique. Maybe your bike is OK.
But here are some more things to think about:
Replace condenser if in doubt.
Check that magneto is set at abrizz (mark on mageto body is aligned with mark on rotating magnet), for strongest spark.