I'm having issues with our 50cc right now - started out as very weak spark (using NGK plug) and now nothing. Started tearing it apart yesterday and using my voltmeter *think* it's a problem with the magneto. Looking for a wiring diagram or schematic that's much more detailed then what was provided in the user manual. Also looking for helpful hints on how to test things like the CDI, Coil and Magneto.

Thanks,
Chris

 

found this thread on bypassing cut off switches. I ve tried it before and it narrowed down a bad kill switch

http://forums.atvconnection.co...0/threadid/463921.cfm

TO BYPASS ALL CUTOFF SWITCHES ON KMX-50, KMX-110, RFX-110

LOCATE CDI

CUT BLACK WIRE WITH WHITE STRIPE CK. FOR SPARK LEAVING ENOUGH WIRE TO RECONNECT.

THIS WILL RULE OUT ALL CUTOFF SWITCHES ON THE ATV INCLUDING: IGNITION SWITCH, HANDLE BAR SWITCH, SIDE CUTOFF (KMX-50 ONLY) REAR CUTOFF( KMX-50 ONLY)

CDI 5 PIN PLUG WIRING DIAGRAM:

1. GREEN- GROUND
2. YELLOW W/BLACK- IGNITION COIL
3. BLACK W/ WHITE- IGNITION KILL
4. BLUE W/ WHITE- IGNITION PICK-UP COIL
5. RED W/BLACK ? STATOR COIL

 

I have a different quad, but the ignition systems on all quads are very similar. Does your CDI look this?



Assuming this is a picture of your CDI, measure the DC voltage on the Kill Switch pin of the CDI. It should be around 50-60 volts while cranking. What you are doing is measuring the CDI ignition power supply inside. If you measure a large voltage at this point is means the stator power winding is OK, none of the Kill switches are activated, and the CDI power supply circuitry inside is OK.

If you don't measure voltage here then use your ohmmeter to look for this line being grounded through one of the kill switches. The kill switches work by shorting the CDI power supply to ground - preventing any spark from being generated. If the kill switch line is not grounded then measure the AC ignition power voltage off the stator. *Important* you must have the stator winding disconnected from the CDI when making this measurement because the CDI yanks this voltage around, and different CDI brands do this differently. Usually there is an in line bullet connector between the stator and the CDI. The stator power winding should be putting out around 80 volts AC while cranking.

Measure the AC voltage on the Timing Trigger pin while cranking. This wire has very narrow +/- 5 high volt pulses on it at a low repetition rate, so your voltmeter wont do a good job of measuring this, but you should see something. I get 0.3 volts AC on my quad, yours should be similar. This voltage can be measured hooked up to the CDI or not. It doesn't matter.

Both the ignition power winding and the trigger winding should measure continuity to engine ground. Mine measures 440 ohms to ground on the ignition power winding, and 140 ohms on the trigger winding. Remember that mine is a different engine so your resistances may be a little different. There is a third winding in the stator, but that is for running the lights and charging the battery - it has nothing to do with ignition.

This should get you started at least.

 

Yes, my CDI does look like this however I will not have any time to look into the problem until the weekend. I did measure my windings, similar to yours - i think 300 and 140 respectively. Again, I'll use the information from both postings to dig a bit deeper into my problems. Thanks for the quick responses!!!