HI New here, so hi all.

I have inherited a 125cc 4 stroke chinese quad. It had no wiring loom so purchased one and followed the simple youtube video. It turns over, lights work but no spark.

Following some simple meter tests I have the following at the input side of CDI loom

AC ignition power pin 495 ohms
timing trigger pin 128 ohms
AC ignition power 56 Volts AC
Timing trigger 0.012 vols AC (?)

My issue is, as soon as I plug a new CDI box in it blows when I try to start (with the plug on the cylinder head searching for a spark). I have replaced the coil, regulator, kill switch,solanoid etc. It is a 5 wire CDI with the loom, but would not know if it was the correct one?

Output side of the cdi loom, ignition coil pin reads 128 ohms, not less than 1.

I have put a new stator on, and replaced all components, even bought a spare set of components / loom to try and identify the issue.

Struggling what to check next if anyone can help please?


thanks




Tim

 

Timing trigger coil voltage seems decidedly feeble, I would guess at at least 0.25v to give a strong enough signal the CDI. However if it is blowing the CDI you must have the earth pin out wrong. CDIs do vary as to which pin goes to what, but if the CDI is supposed to match the loom, this should be right. Did the ignition switch come with the loom? As some CDIs are earth to run, others earth to kill, and the wrong switch will work the wrong way.

 

Many thanks for your reply. I have had to buy more CDI as they kept blowing. All the parts I need such as ignition switch came with the loom. Checked again tonight and zero volts from the trigger, even on my meters lowest setting. I am really at my limit of understanding here.

The weird thing is now I have bought 2 complete wiring looms with all the associated parts and getting the same fault, which suggest to me something else. Is there any way the flywheel can create a short, or am I looking in the wrong area?

thanks



Tim

 

Afraid I don't know much about those "universal wiring looms" I do know Honda themselves used several different stators on the Cub engines and, I guess, several different sized flywheels to suit, so you may have the wrong sized stator for your flywheel. However CDIs only blow if the wiring to them is wrong, and usually because the earth pin isn't connected to a good earth.

 

Thanks again, done continuity from earth pin to frame and all good.


Will keep scratching my head

thanks


Tim