125-200cc SMS 125, no spark.....

Hi.
I'm fixing up a 2007 SMS 125 for a kid. I've replaced the piston and some minor stuff, but now I cant get any spark on the spark plug.
I have done a minor welding job on the frame, because it was cracked. But I disconnected the battery when I did the welding, and hope that would be ok. I have not been f.....cing around with the electrics, so......? Any ideas?

Check coil mounts for rust or dirty connection. After that do an OHMs test on the coil. If that checks out, then check the stator and trigger coil. Most old bikes have old bad connections in the electrical system due to rust or dirt. The coil wire to the spark plug can also get rusty where it connects to the spark plug boot. Also check the kill switch.

Paw Paw

Hi.
It's polite to tell, when the problem is solved; One wire going in to the connection to the ECU was broken, and had some minor contact now and then. Now it's soldered, and the spark is back!