Just got this bike from a mate, its a 50cc quad, the only markings on it are shineray. It started yesterday and I ran it for 5 mins no problem then I stopped it and I haven't had spark since.

I've read some of the threads here and so far what I have done is measure the voltages at the CDI and I have 55ac at the ac ignition power pin and about 0.2ac at the trigger. The ground is definitely earthed and the kill switch input is not but is when the switch is in the off position (its a 5 pin CDI, with the pins all in the one plug). I get about 0.2ohms across the coil from the CDI plug and about 8kohm from each of the input leads to the output of the coil.

I also get only about 3Vac and 1 Vdc on the output of the CDI, ie If I disconnect the coil and measure across those 2 leads. I would think this is where the output of the capacitor should be, so it should be a high voltage (100~200Vdc) is that correct?

So my questions are

--is 55vac high enough to drive the CDI, or is the stator no good?
--are all these 5 pin CDIs the same, as I can buy one that looks exactly the same on ebay to suit a 110~125cc thumpstar?
--If they are not the same where can I buy one to suit the 50cc?

any help will be greatly appreciated.

 

anyone got any ideas please....

 

---55 volts AC is fine.

---All the 5 pin CDIs like the one pictured below are the same. eBay is a good source for these.



The CDI storage capacitor is buried in the CDI. There is a transistor switch that pushes the capacitor charge out the ignition coil pin when the CDI is triggered by the signal on the timing trigger input. When measuring the CDI ignition coil output pin, the coil must be hooked up. The coil primary is part of the charge path for the CDI storage capacitor so the coil must be connected to get any output.

Measure the CDI ouput pin while cranking the engine (kill switches in the run position). Different meters show different things, but most meters will show mostly zero volts, with occasional random numbers in between. This is because the output of the CDI is extremely narrow pulses 100 volt pulses that ring several times at 30 KHz. Meters are not designed to measure this, but most will sample the output pin and capture the CDI at zero volts (where it is most of the time). Occasionally it will capture part or all of the output pulse and display something depending on the meter.

 

thanks for the reply Lynn, I don't see any pulses using a fluke set on max, looks like I need another CDI, I'll give it a try and report back.

thanks again.

 

I am with trying a CDI also.
If the wires are grounded, have good conductivity, and the proper voltages, than I would R&R the CDI.

If after the CDI the quad still does not start than I would make sure that all pins in the connectors are tight and have good contact with the CDI pins. I have had bad CDIs, handlebar kill switches, bad tether kill switches(at the back of the bike on the frame under the seat.), and loose connectors that all have killed my spark.

The stators and pick-up coils with the stator are usually OK but can go bad also. Yours seems to be working fine. Also, the coils go bad sometimes. Having a spare coil/wire around also helps.

Hopefully the CDI replacement fixes the problem.

 

mr firemouth,

thanks for the response I just ordered a new CDI hopefully it'll be here in a week or so. I'm pretty sure the connections are all good.

Another question for anyone and everyone what resistance should a 50cc shineray quad coil be? any ideas?

 

The nice thing about having the generic 5 pin CDI is that means you also have a generic coil. The coil and CDI are tuned to each other, so it means you can use any quad coil with your quad as long as the other quad also uses the same generic 5 pin CDI. You'll have to make it fit mechanically, but other than that they will be the same.

The coil resistances on my generic coil are 0.3 ohms on the primary to ground, and 8700 ohms (8.7K Ohms) on the secondary to ground. This can vary a bit from coil to coil on the primary side. On the secondary side it can vary all over creation. A lot of coils (mine included) have resistors built in to reduce radio interference emissions. Sometimes this resistor is on a removable plastic cap at the spark plug end. Other times it is not removable (like mine). I've never seen one, but some have reported coils with no resistor at all and secondary resistances of 12 to 20 ohms (0.012 to 0.020 K Ohms).

Measuring coil resistances are fine (and useful) when looking for opens or shorts, but it isn't very diagnostic for many common problems. If you have a shorted turn in the primary or secondary it won't affect the resistances much, but it will absolutely kill any spark. The other problem is with high voltage breakdown inside the coil (or sparkplug). You can't measure this with a meter. So the scheme is to measure and find (or eliminate) problems on the low voltage end of things, then if necessary change out the spark plug, coil, and (sometimes) the CDI.

 

Thanks again for the info. My resistances on the coil are much the same as yours 0.3 and 8k7.

I might be lucky and the CDI will do it.

 

its a piece of crap this thing, I got my new CDI and it worked for 5 min. Now no spark again.

I have removed the CDI and tested again and I get about 55vac at the ignition power pin and 0.3v or so at the trigger. Also about 370 ohms ground to ignition power pin and 120 ohms trigger to ground.

I noticed that if I check the ignition power with the CDI in place the volts are 0.7vac, does that sound right?

Anything ideas about anything else I can try, maybe the coil is stuffed although all the resistances are still the same as above?


thanks in advance



ps just ordered a new coil aswell.

 

I had some bad luck with a batch of CDIs. It was driving me crazy. I ordered from another person on ebay and got a different color CDI and it hasn't missed a beat since.

For ME, I had a green looking color CDI and it was 5 pin, I ordered about 5 more from a place and they were a brown looking color and they would last for a few minutes and then crap out. I ordered from another dealer and got a green looking color and , like I said it hasn't quit yet.


Yeah , Yeah , I know color doesn't have anything to do with it, BUT maybe the manufacturer does.