Struggling with diagnosing no spark, not sure where to go from here. The shop that had the bike before me diagnosed a intermittent misfire as a bad coil and replaced it- I don't agree with their assessment. The same coil (rear) that was replaced has no spark at all now (assuming fronts as well, as it won't fire at all). I have tested everything on the coil and all checks out except the primaries, which measure 4ohm (slightly higher than spec, but not sure if enough to matter). Across the boots it's 25kohm, no boots and just wires was 14.xxkohm, confirmed there is 12v at primary also. Any suggestions where to go from here? Checked the CDI unit, connectors were packed full of dielectric but otherwise seemed ok. Bike has only run a few times since I've had it, appears to be an intermittent issue.

Just tested pulse generator and that is within spec from Haynes manual also

Are you getting a pulse through the earth when the engine is running? Assuming you have a meter quick enough to capture it.

doing some more digging, appears the reg/rec is toast- not getting anything for any of the red - yellows on multimeter. If this is fried, could that have taken my CDI with it?

Simple ohms check on rect/reg will give misleading results. Were you using the semiconductor function? Failed rect/reg can cause over voltage that may damage the TCI unit, NC30 does not use a CDI. Sometimes an over voltage fault in the TCI can be detected using the burnt smell test up close to the TCI.

magg wrote: Sun Nov 13, 2022 11:02 pm Simple ohms check on rect/reg will give misleading results. Were you using the semiconductor function? Failed rect/reg can cause over voltage that may damage the TCI unit, NC30 does not use a CDI. Sometimes an over voltage fault in the TCI can be detected using the burnt smell test up close to the TCI.

just following the guide in Haynes manual, multimeter was set to ohms

Reg/rect full of diodes, ohms only range is unsuitable for testing diodes. Most multimeters have a range with a diode symbol which is the only range that will give reliable readings. Any unpleasant aroma or signs of physical distress from the TCI.

Have a diode setting on my multimeter so will poke around with that tomorrow. Nothing looks or smells obviously burnt, either at reg/rec or TCI, but will also take a closer look. Guessing there is not a non-destructive method to getting the TCI cover off? Anything else you'd recommend testing?

Had the ignition switch off, that seems to test OK too.

OEM NC30 TCI unit cover comes off with gentle persuasion, there may be evidence of failure eg blackened or physical damage.

Removed the TCI and popped it out of the cover, no smells and nothing obviously burned. Feel like i'm running out of things to check