Yamaha YP125 Majesty

 Still we struggle to identify why there is no spark at the end of the High Tension Lead.  The bike is equipped with electronic ignition. and to date we have...

1. Soldered a replacement crank position sensor  coil onto the generator back plate and checked that it is producing some AC voltage.  When the engine is spun on the starter it produces 0.7 to 0.9 volts.  This tiny voltage should be enough to tell the ECU to fire the ignition.
2. Checked for continuity from the above mentioned coil to the ECU.  The wires are perfect, although the voltage drops to 0.3 to 0.5 volts by the time the wires reach the ECU.
3. Checked the operation of the sidestand cut out switch - it makes and breaks as it should do.
4. Checked the igntion fuse up near the steering stem.  It is fine and there are 12 volts across the fuse.
5. Checked for voltage at the ignition coil feed  - There is a good 12 volt feed to the coil and the coil is well earthed.
6. Checked for continuity from the coil back to the ECU - There is continuity.
7. Checked the operation of the lean angle sensor - it operates as illustrated in a very useful Youtube video I found which suggests supergluing the magnet inside it in one place - lets see if we can avoid doing that.
8. Checked the lean angle sensor wiring.  Two of the three wires come directly from the ECU.  Both have 5.5 volts running through them.  The third wire doesn't have any voltage and is possibly an earth. We are still not entirely sure how the lean angle sensor does its stuff  as it operates electronically rather  than being an on off switch.

So we seem to have two options - replace the lean angle switch unless we can prove it is functioning correctly or replace the ECU.   Before going to that expense it might worth checking for changes in voltage in the lead from the ECU to the coil or simply trying another ignition coil just in case the new looking coil isn't all its cracked up to be.