Cdi Troupleshooting

[magoconnor]

Hello. 

I have hit a bit of snag trying to get my 139qmb engine running probaly. 
It will fire up, but I can only keep it alive for about 10 sec with the throttle.
The idle is extreamly rough and it sounds like its not firing right. 
So I wanna go ahead and check the cdi. 

Can anybody tell me what the voltage I should preferably see at each wire. 
Im  espeasially curious about the trigger/pick wire and the ac power wire. 
Also after seeing various diagrams, I have spotted that sometimes the 3. slot on the cdi ( under the trigger wire ) is also used as ground. 
Is this necessary? Cause right now Im only using the 4. slot as ground. 


Tho I know, its almost never the cdi, I have already ruled out almost els. 
So its really only whats left. 

[Rune 75]

Can't help with the wiring but I have had 3 cdi's make the scooter run like crap over the years, so it can definitely be the cdi.

[magoconnor]

I just need to know the normal vac measured, at the pickup/trigger wire and at the cdi ac power wire.
So I can check if its my cdi or my magneto.

[jackrides]

Just a thought. Most digital volt meters have a 'HZ' setting. That is 'Hertz' the modern name for pulses (or frequency) per second. That could be used to check what the pickup is sending to the CDI, and the CDI is sending to the Ig. coil.
I recently tried this on a 2004 Ford 3.0 to check on the Ig.coils and fuel injectors. Seemed to work.