If it worked on the stand with the old stator then the problem isn’t with the stator. We’re so quick to replace everything nowadays!
If if I had to guess, no spark means the green (ignition) wire in the loom is shorting to ground. A simple check is to hold the green from the stator to the frame and see if you get a spark jump. It should because you said it was running.
A 125 special should have a key ignition switch. Make sure it’s in the ON, one or more click to the right of center position (sounds obvious I know but you wouldn’t be the first)
If that doesn’t work then separate the loom out of the problem. Process of elimination. Only connect the green wire from the stator to the coil and coil to ground. This way it’s basically like you had it on the stand. From there start putting it back together. At some point it will stop running and there’s your problem.
There's a lot that could be going on here. Best to walk through it step by step.
- Check the condition of wires on stator. Any signs of rubbing, pinched wires, or shorts (scorching)?
-Ensure points are operating properly -- test with bulb or voltage meter. - Is the flywheel properly mounted and torqued down?
- Is the Stator properly grounded?
- Is the engine properly grounded?
- Do you have power from the stator to the coil? Check with bulb or voltmeter.
-Swap to a different spark plug and re-test.
-Swap Condenser and retest -- I've had no end of trouble with new condensers that are bad.
Hello, and thank you all in advance - long short, I rebuilt the motor on a ‘68 125 Special and replaced almost every part of the engine, all wires, etc - except bodywork.
I started it outside of the bike on a metal stand that was built and it ran strong - now once on the bile, it will not get any spark (have the plug out, connected to new coil and kicked it over but 0 - zero - spark. Even found a never used stator from Italy, put new points and condensor, but will not kick over... been at it for many many weekends, too crazy... thoughts? Ground is good and the ignition was fairly new prior to the rebuild, too strange... Vince
Ok thanks Stu, I’ll open the headset and look for cracks. It seems to ride fine and no binding in steering or controls. He took off but my buddy got his plate number and cops tracked him down. He said he didn’t know he hit it.