GY6 150CC 157QMJ No Spark

[datapro]

Can someone explain or is there already a post explaining just how the CDI works?  I have searched but don't seem to find what I'm looking for.

I have a 150CC Lance 157QMJ GY6 scooter.  It started earlier this season and ran.  I shut it down, now it will not start.  I do not have a spark going to the spark plug.  I have replaced the CDI, Stator, and Ignition coil with new replacement parts.  I found an explanation on YouTube that describes how a CDI works and it indicates that AC power from the stator is rectified inside the CDI and charges a capacitor.  This makes sense.  When the ignition timing coil sends a pulse to the SCR (in the CDI), the Capacitor discharges to the ignition coil.  Also makes sense.  I do not have any AC goint to the Power Input of the CDI (6-Pin).  I have traced the three phases from the Stator Coil and they go to the Regulator / Rectifier (4-Pin).  There doesn't seem to be a connection from any Stator coil to the CDI, for power, as described in the You Tube video.  OK, maybe a bad regulator / rectifier ?!?!  I then replaced the Regulator / Rectifier with a new one, and it now blows fuses ?!?!

Should I have AC or 12VDC going to the CDI?  I understand the basis concept of CDI ignition, but I just don't know if the CDI should have an AC (from the Stator) or 12 VDC from the ignition switch.  Again, the three phases from the Stator go directly to the Regulator / Rectifier.  

[90GTVert]

There are both AC and DC CDIs for GY6 scooters. The AC CDIs get the power for spark from the exciter coil in the stator. The DC CDIs use 12VDC from the battery. Both will have a pickup wire to time/trigger the spark. The AC units will have a wire that is commonly black/red or red/black for the exciter output to the CDI.

Both usually have a 4+2 pin connector. The 2 pin section should have either the AC exciter power wire in it or a wire that shows 12V+ when the key is on... or continuity to the key on power circuit.


Blowing fuses after the reg/rec swap may just mean you got the wrong one. I'd try changing the fuse and putting the old one back in. The reg/rec shouldn't cause a no spark condition, even in a DC CDI scoot as long as there's battery power.

[datapro]

Can I assume that since all three phases of the Stator go to the rectifier, I have a DC CDI? The CDI IS a 4 + 2 pin arrangement.

Thanks for the reply...

[snaker]

While some GY6 150's do have 3 phase stator/rr combo's, its fairly rare. How sure are you of that.

Some photos of wires and wire landings at the stator, rr, and cdi would be helpful.

[datapro]

There are three wires coming out of the stator.  There are also the other ends of the same three wires soldered together inside the stator.  This is a 12 coil stator.  Continuity of all of the windings are good.  It's a new stator.  There is no resistance from any widing to ground out of the bike.  All three wires are yellow and can be traced directly to the Regulator / Rectifier.

[snaker]

Aug 2, 2020 22:39:16 GMT -5 datapro said:

There are three wires coming out of the stator.  There are also the other ends of the same three wires soldered together inside the stator.  This is a 12 coil stator.  Continuity of all of the windings are good.  It's a new stator.  There is no resistance from any widing to ground out of the bike.  All three wires are yellow and can be traced directly to the Regulator / Rectifier.

Your description is solid evidence that it doesn't have a dedicated AC CDI power coil, assuming the new is a proper replacement. (The RR and stator also must match)
If no AC from stator then the CDI is DC powered.

[datapro]

Thanks to all who responded. I'm going to assume that I either received the wrong CDI or the new CDI is damaged. I have since measured 12 VDC going to the power input of the CDI when the ignition is on. I need to purchase another CDI and make sure it is a 'DC' cdi. Fingers crossed...