So the other day I was riding my 110, after several miles it died suddenly. changed plugs, nothing...in the garage it goes. I disconnected kill wire on CDI, cranked over, all I get is weak/ intermittent spark. I disconnected the stator and started testing. #1(batt chg. winding) 1.0VAC, #2(ign. trig) .19VAC, #3(AC ign. power) 49VAC. Looking for opinions? Every thing looks low to me, but isn't that a little weird for multiple coils to go at once? Thanks

 

The battery charge winding is really low, but this has nothing to do with spark so you can ignore that for now. But did you measure between the two battery charge output wires, or from each to ground. You should be measuring from each to ground on 110cc machines. Other engine size battery charge windings are measured differently.

49 volts AC for ignition power sounds fine.

0.19 volts is OK also since you are getting spark (even be it intermittent or weak). This voltage depends a lot on the meter used since it is a complex waveform instead of the clean sine waves that meters are presumed to be measuring. This is a trigger signal, so if a particular trigger is too low then you won't get a spark at all. If it is high enough you get an entire spark (not a weak spark). It's all or nothing. Also, this trigger signal voltage is directly proportional to engine RPM's, so even if it was marginal as long as the engine caught once and increased the engine RPMs the next trigger signal would get bigger and it would fire continuously and start up. And of course idle speed is 2.5 times the cranking speed so end of problem there.

Weak intermittent spark is tough to troubleshoot other than through changing out parts because you can't measure anything. "No spark" problems by comparison are much easier.

I'd start with the cheapest first and progress on up: Spark plug, then coil, then CDI. Its nice to have spares anyway.

And since you are measuring things unplugged and testing them plugged in, it would be worthwhile to make sure all your contacts are clean and tight at the CDI (including the ground wire).

 

Thanks for the response, I tested the batt charge winding yellow to white wires, i'll retest to ground. I have a Z50 also I pulled the coil off and tried, but It was the same. A new CDI is on the way, I ordered a 5 pin "high performance" CDI, any 5 pin AC CDI will work will they not?

 

Yes, to the best of my knowledge.