This thing lost spark when my daughter was riding it. I put on a new cdi box, Tested stator, coil, And checked wires and switches but have had no luck. Cant find a wire diagram for this quad but found a jog 50 yahmaha diagram witch I belive is the same engine but not sure if everything is the same. Any ideas?

 

I've never seen a wiring diagram for your quad. I'm curious about where you got a new CDI. There was thread a few months back about a 90cc sundiro sunray which used a really unusual CDI. I'm wondering if your 50cc quad uses the more generic chinese CDI, or one of the strange ones. Can you post a picture of your CDI, or a link to where this CDI can be bought?

How did you test the stator, coil, switches and wires? Did you use a meter? What are the results of your measurements? How was your meter set? What pins did you measure and under what conditions?

 

I had a electricion at my work test the stator for me, The coil I just tried one off somthing else, as for switches I just bypased and was only able to look at wires cause Im dont have a meter. The cdi box can be found on ebay along with manny other engine parts. It is a yamaha part but the sundiro is basicaly a yahmaha engine. here is the link. Motorcycle CDI JOG 50 Yamaha: eBay Motors (item 300469087906 end time Sep-19-10 20:28:25 PDT)

 

That CDI is definately not any of the common chinese CDIs.

You say you tested everything in the ignition system (except the spark plug), and you still have no spark. You could try changing the spark plug, but then you're back to square one.

You really need a meter. Many electrical problems cannot be found by just looking. You have to measure. Meters are really cheap. There is no excuse for not having a meter. See this link:

7 Function Digital Multimeter

The stator does three things:

1) It makes high voltage AC (100 volts or so) for powering the CDI.
2) It makes a trigger signal (low voltage AC pulses) fro telling the CDI when to fire.
3) It makes low voltage high current AC to charge the battery through the voltage regulator.

The low voltage battery charge part of the stator ( #3 above ) has nothing to do with making spark and can be ignored for this problem.

I would start by measuring the high voltage supply wire while cranking at the CDI (with the CDI disconnected). This would be high voltage AC so set your meter accordingly. Then I would measure the trigger signal to see if it is working. This would be a low voltage AC signal probably measuring less than 1 volts AC - but it shouldn't be zero volts.

I don't have a wiring diagram for your quad. You might have to futz around to find which wires are what. Look at the main harness wire colors at the CDI, then look at the main harness wires colors at the stator. You should find two that match (and maybe a ground too - usually black). One of them has to be the high voltage AC power, and one the trigger signal. Measure them while cranking the engine and see what you get.

Look at this thread and see if the colors match yours at the CDI:

http://forums.atvconnection.com/kids...g-diagram.html

Scroll down and look at the TobyCheeseman post. Do the colors match? If they do it may help guide us with future tests. The thread is for a Monsoon quad, but elsewhere I've read that the Monsoon and Sundiro were said to use the same CDI.

 

Helped a friend with a similar problem on his grandson’s 1999 50cc Sundiro. Could not find a wiring diagram on the net, so we uncovered and disassemble the wiring. I have attached the wiring that I found and have drawn out on his Sundiro. What we found was a shorted carb solenoid that was drawing all our voltage away from the voltage regulator. I also found an issue in the on/off on handle bar.
Ours now starts and runs, but it is rich. Trying to understand the carb/solenoid. Would appreciate if someone can explain what the pin under the solenoid does? By the wiring diagram it looks to be pulled up as soon as you try and start the wheeler?
No guarantees on the wiring diagram, it is what I found on the wheeler I was working on…. Good Luck!
sorry not sure how to attach a file (new to this), so follow the url.

http://www.flickr.com/photos/omansracing/5015196166/

 

Thanks for posting the wiring diagram. It looks very thorough and makes perfect sense (unlike many published diagrams from other quad manufactures which have glaring errors).

Does your carburetor 'solenoid' look something like this?

http://forums.atvconnection.com/attachment.php?attachmentid=3982&stc=1&d=128521469 0

The unit in question is labeled as a "bystarter valve".

If so, see this link for an explanation of how it works (scroll down a ways to get to the relavent stuff):

http://forums.atvconnection.com/kids-quads-other-atvs-ask-expert/330045-eton-90-thunder.html

Bystarter valves often fail in the "enriched" mode. Wax expansion pellet could be bad, or the heater could be open, or the wiring to the heater could be open.

 

I could not open your first link, it gave me an invalid attachment message. But from what you describe in the second, this is what we have. Our unit shorted, once we unplugged it, we had spark. The unit seems to have failed out, as when we had it on the bench, we could push pin and plunger up into the solenoid and a light spring would push it back out.
Thank you for the explanation and help.