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Problem with ignition (SEM), weak spark

Joined Aug 2004
32 Posts | 0+
Kristinehamn, Sweden
I have read some of the posts regarding the SEM ignition system. I have a FE501-02 with SEM ignition. Last year i had to replace the stator and "flywheel" because of a failure in the charging coil. Everything has worked fine until a a week ago when the bike suddenly stopped and was impossible to start. After some minutes it started again but stopped again. Now it runs, but it can only be started with the electrical starter (only sometimes with the kick). I suspect a submersion during a race three weeks ago, but the berg has worked fine after that (After oil change, clean carburator, drying all parts etc.) I have changed the ignition cap and wire, but no major difference. I have also measured the resistances in the coils and the are all fine. The output from the coils (measured with a multimeter on AC) when cranking with the electrical starter is ~3V from the pickup coil (the green wire) and ~30 V from the charging coil (the red wire). I can also see sparks in the spark plug when cranking with the electrical starter but not (or seldom) when using the kick. Is this likely to be a problem with the CDI? When cranking with electrical starter the CDI is fed with 12V, is this the reason for sparks only when using the starter? Also when running the engine at very low revs it stops.
 
Hi i think i have the same problem, same bike. Did you find any result on your problem.

Greetings from Iceland

Gisli
 
I have now located the problem which seems to be quite rare compared to the other "normal" SEM problems. The Husaberg dealer in Laxå (Sweden) borrowed be complete set of SEM parts to perform the trouble shooting (thanks for that). I then compared voltages etc. changing one part at time. Eventually I found out that the problem was the "CDI". After replacement the bike now works fine.

The problem was that the bike started with the electrical starter but not with the kick. This depends on that 12 V is feed to the CDI when activating the electrical starter and causing the rpm to get a spark to lower ~300 rpm. The bike also stopped suddenly at idle. The failure also seems to be temperature dependent since the bike sometimes started on the kick when cold. I'm not very familiar with the design of the CDI (capacitor/coil with some electronics) why I can't speculate in possible reasons for the peculiar behavior. The dealer also said that it's not very common that the CDI breaks.
 

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