Trying to diagnose a "no spark" problem, and want to test the plug that goes into the CDI. From what I've been able to research, it's a DC, 4 wire setup. I have a voltmeter and know how to use it a bit and can give you the readings if someone tells me what to test.

The quad is a 110cc, Loncin. I believe there is no 12 volts coming into the harness, but need specific instructions how to verify that.

Appreciate all the help

PS. Sorry if this is posted in a different forum. Still figuring out the forum setup.

 

The system is almost identical to a 1980s car. Ignition live through a fuse and ignition switch goes to CDI, an earth is also connected to CDI, another wire runs from the trigger coil on the flywheel to tell the CDI when to fire, and an output wire runs from the CDI to the coil for the spark. Usually this wire gives a negative pulse and the other coil terminal is fed live from the ignition switch. Many, though not all, Chinese bikes use the Honda wiring colours, Red or Pink is live. Green is earth. Blue/Yellow from trigger coil, and Black/White to coil.

 

Would this be the same 12V coming in on an AC as well as a DC setup?

 

No, AC setups vary, but AC power is fed direct from the alternator, sometimes a tapping from the three phase unit which powers the battery, sometimes the CDI has an alternator coil all to itself, this coil feeds whatever AC voltage it is making into the CDI, often 50v or more and, of course, only occurs when the engine is spinning over.

 

Thanks for the info. I think the next logical question is what am I supposed to get for values on the 4 wires incoming to the CDI unit ???

There's a GREEN for ground. A BLUE/WHITE (I believe it goes to the stator as a "trigger"). There's a black/white that goes to the coil. There's also a YELLOW which I believe is the 12V DC supply, could be wrong though.

 

Right, you should get 12v between the green and the yellow with ignition on. When the engine is turned over on the starter you should get an AC voltage pulse between the blue/white and the green, some say over 0.2v some recon get 50v, but you should get a voltage. With CDI plugged in, you should get a pulsed voltage between the two wires going to the ignition coil, of at least 12v when the engine is turned over.

 

Great news. Since the yellow wire to ground didn't get me 12v DC, I ran a tester wire from the battery + post directly to CDI plug and bam.... I now have spark.