I have an MPX-90 and it started to stall out while riding. This went on for about 2 days. It would restart quickly at first than got worse to the point it won't start at all. I have an oscilloscope hooked up to the trigger on the coil but don't know what I am looking for.

Is it supposed to have an AC or DC signal?

Are there any problems with the CDI boxes?

Does anyone have a wiring diagram?

Please help my kids are really wanting to ride it.

Thank You Brady

 

Is this a picture of your CDI?



If so, this is what you see at the Ignition coil pin using an oscilloscope:



There are two waveforms beacuse I have two working CDI's that work the same with very different output waveforms. CDI's should be thought of as black boxes that perform a task, with may ways of accomplishing that task. By far, though, CDI #2 is the most common design out there.

Seeing that you're armed with an oscilloscope I would also look at this waveform on the CDI:



The CDI output waveform to the coil won't happen unless you get the trigger pulse to tell the CDI when to fire.

 

Your wiring is probably similar to this, though the wire colors may not match:



This diagram is for a 110cc giovanni, though often wiring between quads is very similar.

 

Thank You I checked the trigger and it looks just like the wave you have the picture of. The output from the CDI is not pretty and is all jaged and all over the place so I am going to replace it and see what happens. Thanks Again.

Do you know where a good place is to get parts?

I have many Quads and need a good supplier. I can get comercial wholesale account because I work at The University of Northwestern Ohio.

 

I buy generic parts such as this from eBay. Windtrader started a list of parts suppliers in the Chinese Quad section (it's a 'sticky' thread at the top). You should look there too. Hopefully this list will grow over time.

 

Thank You very much I orderd the CDI box after having a friend who has the same quad test it on his.